1. WHO IS THIS BOOK FOR?

This FAQ answers common questions in a readable way for ordinary people and anyone interested in (slowing down) fossil-fuel use, greenhouse gas (GHG) emissions, atmospheric GHG concentration, and climate change.

2. WHO SHOULD I CONTACT IF I FIND A FACTUAL MISTAKE?

Check that it is not a minor disagreement among different data sources. If it is not, please email the author, Ivo Welch, with a specific authoritative reference. (Please do not email the author with opinions, especially one that it is dangerous to tell the truth because it will corrupt them.)

3. WILL THERE BE A NEW EDITION?

Yes. I plan to update this FAQ about every three months. (This current edition is from 2024-02-23.) This is partly to improve the current edition; partly to reflect new information. Unfortunately, Amazon does not seem to make it possible to provide new editions free to previous edition purchasers. Thus, the price of this FAQ is kept deliberately low. Be aware that this means you may want to repurchase it every other year or so.

4. WHERE CAN YOU FIND SOURCES, MORE INFORMATION, ETC?

More detailed information (including sources) can be found in

Ivo Welch and Bradford Cornell, 2022, Global Climate Change: The Pragmatist’s Guide to Moving the Needle.

available for purchase on Amazon or on the authors’ website, https://www.climate-change.world.

5. WHERE CAN YOU FIND A SUMMARY OF IMPORTANT FACTS?

There is a small appendix at the end of this FAQ. A better and longer one appears in https://climate-change.world/, which contains a 5-10 page appendix that summarizes the most important facts concerning climate change — such as facts about population, emissions, warming, economic impacts, and technologies, and so on.

6. CAN YOU TRUST SCIENCE AND SCIENTISTS?

It is not true that scientists are perfectly objective. Scientific communities often form groups that are intent on promoting certain explanations. However, the process of scientific skepticism is designed to help reduce biases. It is not perfect. Nevertheless, compared to other non-scientific groups, scientists tend to be less biased. Science is the best that humanity has got.

7. HOW CAN YOU HAVE FAITH IN SCIENTISTS WHEN THEY ARE DISAGREEING?

The process of science is about skepticism. Informed disagreement should not be confused with lack of trust or lack of informedness. On the contrary: unless it is abused by uninformed individuals to promote crank science to outsiders, disagreement is often a sign of healthy science. Unfortunately, in their search for certainty, the media and the public often misinterpret the scientific mode of discourse.

8. CAN YOU TRUST CLIMATE SCIENCE AND SCIENTISTS?

Although outsiders (especially fossil-fuel interests and donors) have tried to politicize climate science and spread doubt and confusion — and even reduced the willingness of climate scientists to publicly debate (because trolls will always remain unconvinced by evidence) — climate science overall is healthy. Simply put, although not perfect, climate science has been and continues to be good science.

9. CAN YOU TRUST ECONOMICS AND ECONOMISTS?

Read what I just wrote about climate science. The same holds true of economics and economists — my own primary discipline.

10. CAN YOU TRUST ENGINEERS AND TECHNOLOGY INNOVATORS?

Read what I just wrote about climate science and economics. The same holds true of engineers and technology innovators.

11. CAN YOU TRUST ME (THE AUTHOR OF THIS FAQ)?

As I noted earlier, I use the icon to warn the reader when my opinions are more controversial and disputable.

I have made every attempt to remain as objective and undogmatic as possible. Not only have I not accepted financial support from anyone or have a conflict of interest,1 but I am also not beholden to anyone. However, as with anyone else, you should check any statements that do not seem correct to you with other credible sources and make up your own mind.

12. CAN YOU TRUST THE MEDIA?

Few of the major media outlets publish outright false reports in their non-editorial content. More commonly, the major media are eager to publish spectacular news. They have a bias that neglects the “boring” non-findings.

Be aware that fossil fuel companies support a public-relation industry that downplays the problems of fossil fuels and exaggerates the problems of clean energy. Other less-well funded organizations, media, and editorials cater to audiences that are eager to hear only about the harm of fossil fuels.

Beyond the largest media outfits, whose ingrained biases are familiar to most readers, the Internet quickly becomes dangerous territory. It is rarely clear whether news comes from a biased or an unbiased source. Much is surreptitiously primed and fanned by actors in foreign countries.

13. THE MEDIA REPORTS THAT HUMANKIND NEEDS TO DO X. IS THIS CORRECT?

The question is futile. As will be explained below, humankind is not a coherent entity that can make decisions. The statement “The world should…” is not a productive way to analyze real-world decision-making.

14. THE MEDIA REPORTS THAT HUMANKIND NEEDS TO STOP USING FOSSIL FUELS BECAUSE EARTH IS SUFFERING DROUGHTS, SEA-LEVEL RISE, ETC. IS THIS CORRECT?

Even if the question were not futile, the answer would also be unclear. The details will be elaborated on below.

• It is true in the sense that reductions in fossil fuel use would make a modest but notable difference in about 50-100 years.
• It is false in the sense that even drastic fossil-fuel reductions could make a difference that our generation would still notice. As a treatment for droughts, fossil-fuel reduction is akin to prescribing a child with a broken leg to exercise more in order to live a long life. Exercise is good, but it won’t address the immediate symptoms.

15. WHAT DO YOU LIKE TO READ?

I am partial to reading The Economist (not free), Ars Technica (free), the MIT Technology Review (not free), the New York Times (not free), Science Daily (free), and The Guardian (free).

I do not like Editorial Pages, including those of the Wall Street Journal, the Washington Post, the New York Times, Fox, and CNN. These are nowadays more about riling up the faithful than about presenting thoughtful opinions. They usually present half-truths — only one side of a dilemma. And yes, just as they intend, they also sometimes succeed in riling me up although I should know better.

I also often look at more specialized sites, like https://ourworldindata.org/, https://skepticalscience.com/, https://www.realclimate.org, and https://carbonmonitor.org/.

16. WHAT CLIMATE-CHANGE BOOKS DO YOU LIKE?

Although I must admit that I often prefer to read the journals and magazines mentioned above, I also do like many climate-change-related books. The IPCC reports are too long, but their syntheses and executive summaries are quite readable and in many ways the most authoritative report. This is even though Koonin’s Unsettled critiques some of the IPCC inferences and uncertainties. Pindyck’s Climate Future is about uncertainty in all aspects of climate change (including the economic aspects). Bill Gates describes his own philanthropic ventures well in his own book. Bjorn Lomborg has interesting things to say — and he said it at a time when he was among very few intellectually honest critics of climate alarmism. (And he paid a price in terms of scathing and scathingly incorrect reviews.) And I obviously like our own Global Climate Change book! Even my mother thinks it’s great!

17. IS EVERYTHING THAT CLIMATE ACTIVISTS OR FOSSIL-FUEL PROPONENTS ARE SAYING BIASED AND WRONG?

Much of it is indeed biased. Some of it is wrong. The fact that some or even much of it is wrong does not mean that everything is wrong. (“They used to claim X. Now they claim Y. Thus, Y must be wrong, too.”) Yes, even fossil-fuel proponents sometimes point out inconvenient truths, although they tend to do so only when it is in their interest.

A non-sequitur is the statement that just because X proponents claimed something wrong in the past, they must not be listened to. The statements that are not worth listening to are those that are ignorant, or ignore facts, or distort them because of malintent that they should better be ignored.

Personal opinion: 80% of what fossil-fuel companies are propagating is false, and 40% of what (non-scientist) climate activists are propagating is false. In the case of the former, the cause is typically primarily ideology and money. In the case of the latter, the cause is typically primarily ideology and ignorance.

18. WHAT IS THE GLOBAL MEAN TEMPERATURE?

It is an average temperature statistic over all regions of the globe. This means that Earth would have warmed more in some places and less in other places than the global mean temperature.

19. HOW HAS WORLD’S TEMPERATURE INCREASED? HOW WILL IT INCREASE?

The world global mean temperature has indeed increased. Relative to a baseline of 1980:

(The estimated numbers are from the RCP 6 put together by scientists from the IPCC.)

20. DO SCIENTISTS DISAGREE ABOUT THE FACT OF GLOBAL WARMING?

Satellites and weather stations have provided near-perfect 24/7 measurements for decades. They leave little room for doubt (a) that Earth has warmed up by about 1°C over the last 50 years, and (b) that Earth is still absorbing more solar energy than it is giving off — like a kettle on a stove that has not yet reached its temperature equilibrium.

Therefore, scientists are practically certain that Earth has been, is, and will be still warming up. Depending on the scenario, the already-manifested 1°C is expected to be only about 1/4 to 1/2 of the total ultimate temperature increase due to anthropogenic (human-made) greenhouse gas emissions. (Thus, scientists expect another 1-3°C in global warming, with 2°C perhaps the most likely and activists advocating for an effort to stay at 1.5°C.)

21. WHERE HAS MOST WARMING OCCURRED?

Although the entire globe has warmed, warming has been stronger in the Northern latitudes — such as Canada, Europe, and Siberia. A NASA map shows this:

22. DO SCIENTISTS AGREE THAT THE ATMOSPHERIC CONCENTRATION OF GREENHOUSE GASES AND THE RESULTING (CURRENT) GLOBAL WARMING ARE ANTHROPOGENIC?

The overwhelming majority of Earth scientists believe that global warming is completely anthropogenic. A small minority believe that warming is not entirely anthropogenic (Earth is a complex system!), but even they believe that the man-made component is playing a large role. Scientists also agree universally that a reduction in atmospheric greenhouse gases would cause a reduction in global warming. The greenhouse gas effect is not under dispute. It is solidly backed up by both theoretical physics and empirical evidence.

23. COULD EARTH TURN INTO A VENUS-LIKE HELL DUE TO HUMAN EMISSIONS

Venus indeed suffered from a CO₂-based run-away greenhouse gas effect. This is because once it ran out of water, it could no longer pull CO₂ back out of the atmosphere. Thus, about 98% of its atmosphere turned into CO2.

In contrast, we are worried about humans pushing the CO₂ concentration to 800 parts per million. In other words, don’t worry. This is not possible. (In a few billion years, it will occur, but not because of us puny ants.)

24. DOES WATER VAPOR (NOT) CAUSE MORE WARMING THAN CARBON DIOXIDE?

Think of water vapor as the humidity in the air. Water vapor indeed causes about three times as much warming as CO₂. Water vapor increases when temperature increases. Thus, as anthropogenic CO₂ and other greenhouse gases have raised the global temperature by a little (“primed it”), the resulting increase in water vapor has tripled their direct effect on global warming. Humanity is not known to have influenced water vapor in ways other than through its GHG priming.

25. DO SCIENTISTS UNDERSTAND THE ROLE OF WATER VAPOR?

Scientists know a lot but they do not yet fully understand the entire role of water in the air. There are still uncertainties about such issues as to how clouds form and influence global warming on a global level.

26. WHAT IS THE “CLIMATE SENSITIVITY”?

The climate sensitivity is the temperature change that a doubling of CO₂ causes, including through the secondary effect of water vapor caused by CO₂ priming. The most common estimate of climate sensitivity is 3°C, but numbers between 2°C and 4°C are plausible alternatives. (Scientists are not sure.)

27. IS EARTH IN AN ICE AGE?

An ice age is defined by year-round ice on the poles. This was the case for about 15% of its existence. Planet Earth has been in an ice age for the last 50 million years. Modern mammals developed in this ice age. All of today’s mammals — including humans — have never known anything other than this ice age.

Warmer areas within ice ages are marked by receding glaciers. The “little ice age” of the middle ages is a misnomer. It did not usher in a new ice age. It was simply a little cooler (in Europe). Earth is currently in a very warm part within its long-lasting ice age.

28. HAVE SIMILAR INCREASES IN TEMPERATURE (AS NOW FORECAST) HAPPENED BEFORE?

More extreme increases in global temperature than those forecast now have occurred many times, even in human history. About 10,000 years ago, when Earth came out of its last glacial period (a cold period within our current ice age), it warmed by about 6°C. Since then, human civilization has experienced an long unusually stable period with only modest temperature changes. The current anthropogenic increase is expected to heat the planet by another 2-4°C on top of the 6°C. Like the last 6°C rise, this 2-4°C will likely greatly change the face of the planet.

29. WHAT IS THE FAMOUS “HOCKEY-STICK GRAPH”?

The hockey-stick graph shows that temperatures (plotted in blue) modestly declined from about 500 CE to about 1800 CE, and then turned drastically upward — mimicking the shape of a hockey stick. (A similar pattern shows for the CO₂ concentration in the atmosphere, plotted in red.) This evidence was primarily documented through the work of Michael Mann at Penn State University and his co-authors.

30. WHAT IS NEFARIOUS ABOUT THE “HOCKEY-STICK” GRAPH?

There was a criminal breach of private email conversations among the academic authors. These emails were then distorted and incorrectly claimed by biased media as suggesting that there were issues with the data or the graph or that there was something that the authors were trying to hide. These accusations were baseless.

Thus, as far as the science is concerned, there is nothing nefarious about the hockey-stick graph. (Stop believing everything on Fox News!) The hockey-stick graph pattern has also been independently replicated by other scientists. It is among the most solidly documented climate findings there are.

31. HOW DID CARBON DIOXIDE AND TEMPERATURE MOVE OVER THE PAST 400,000 YEARS?

Here is the graph:

The two were strongly in sync.

32. DOES THE 400,000-YEAR GRAPH SHOW THAT CARBON DIOXIDE HAS DRIVEN EARTH’S TEMPERATURE?

Although the two lines move together, the 400,000-year graph does not show that CO₂ changes have caused temperature changes. This is because temperature changes also drive CO₂ changes, and some other factors may have been driving both CO₂ and temperature. Thus, this graph can be used in very misleading fashion as evidence of the role of CO₂ on global warming. The real evidence for the effects of anthropogenic CO₂ comes from the last 300 years (see the hockey-stick graph), where we know that the CO₂ increase was caused by human burning of fossil fuels and not some other factors.

33. HAVE CLIMATE MODELS (NOT) ALWAYS BEEN WRONG?

Climate models have been pretty much on the money predicting global temperature for at least 50 years now. It is indeed possible to find some models here or there that are “outliers” (either predicting another ice age or cataclysmic warming), but the average forecast over many published climate models has predicted quite well.

The models have also been improving, as have our measurements of Earth’s climate. There is very little scientific disagreement (and uncertainty) about the fact that global warming has occurred and will be continuing. However, past performance is no guarantee of future performance. Longer-term forecasts could also turn out to be wrong. Scientists recognize that they remain uncertain. Nevertheless, the best estimate now is that earth will be warming not just over the next few decades but for quite a bit longer.

34. WHAT WAS THE “GLOBAL HIATUS”?

The “global hiatus” was a temporary slowing down of global warming from around 1998 to about 2012. (This can be seen in the hockeystick graph in Q 31.) Since then, global warming has strongly resumed. Scientists have offered some explanations for the hiatus (e.g., data issues), but there are also still some unanswered questions. In any case, global warming has accelerated since about 2010.

35. WHOSE FAULT IS GLOBAL WARMING? WHO IS TO BLAME?

This is a red herring. It is an irrelevant misleading distraction for purposes of influencing emissions.

Does it matter whose fault global warming is? Even if it could be determined that it was the fault of this or that country, do you believe the citizens of that country would nod in contrition and voluntarily pay for the damage? This is not only the case for past emissions but also the case for the large increase in emissions and warming that is about to occur over the next generation.

It is unimportant whose fault it was. It is only important to reduce global warming from where it is heading now.

36. WHY SHOULD HUMANITY WORRY ABOUT THE GLOBAL TEMPERATURE INCREASE?

Humanity should worry about global temperature increases because the biosphere in many regions will change dramatically. Some areas will become more hospitable, others less so. Although drastic climate changes have not been uncommon even in human history, they have (fortunately) been relatively limited and uncommon for the last 5,000-10,000 years — roughly since the onset of human civilization in Mesopotamia. Our children will be the first in hundreds of generations to experience more dramatic climate changes again.

The current increases also raises further concerns:

• The planet is already as warm today as it has been since the arrival of mammals — and now it is warming further.
• This temperature not seen for hundreds of thousands of years could trigger feedback loops and tipping points that have been dormant and that could make global warming far worse than scientists expect. The small probability of a much larger change occurring may be more worrisome than even the (dreadful) effects of the predicted warming.1
• The speed of the increase will not only wipe out many habitats and species, but it can also in itself trigger further unknown consequences.

37. WHAT IS EARTH’S OPTIMAL TEMPERATURE?

It is a surprisingly difficult to determine what the Earth’s optimal temperature is. It is not even clear what the objective function is. Polar bears prefer lower temperatures than apes. However, from a human perspective, the optimal temperature is likely not 6°C colder than it is today (and as it was during the last glacial age 10,000 years ago). It is a reasonable view that the optimal temperature is not much warmer than it is today. A related reasonable view is that any temperature change — positive or negative — itself likely causes increased adaptation costs and is therefore undesirable. In this case, the optimal temperature (within reason) is always about whatever it is at the moment.

As always, rich people will be better equipped to adapt to changing conditions of any kind. Thus, much of the brunt of temperature changes will be borne by poor people more than rich people.

38. HOW MUCH GLOBAL WARMING DO SCIENTISTS EXPECT?

The scientists’ most likely scenario (called RCP 6) predicts a global temperature increase of about 3°C by 2100 (relative to 1980), of which about 1°C has already occurred. Thus, expect another 2°C of global warming by this century’s end. Earth could heat another 1-2 degrees in the century thereafter. (By then, fossil fuels will likely no longer be in use. This means that emissions, CO₂ levels, and global temperature should decrease again thereafter.)

39. HOW LONG DOES IT TAKE FOR GREENHOUSE GASES TO RAISE EARTH’S TEMPERATURE?

The effect of raising the concentration of CO₂ in the atmosphere is not instant. It takes a few decades until the world responds — sort of like a kettle that takes a while to start boiling. Similarly, reductions in greenhouse gases will also require a few decades before they will have an effect.

40. WILL GLOBAL WARMING CAUSE MORE SERIOUS DROUGHTS, FLOODS, AND HURRICANES?

Global warming will likely eventually cause more serious droughts, floods, and hurricanes. A more energetic Earth will experience more energetic weather swings. However, so far, the global evidence (rather than local evidence, e.g., as in Europe’s recent heat waves) remains modest. For example, so far, tropical cyclones have been more intense (especially category 3, though not 4 and 5), but not more frequent.

41. ARE MORE PEOPLE DYING TODAY OF CLIMATE-RELATED CHANGE (E.G., NATURAL CATASTROPHES, DROUGHTS, ETC.) THAN IN THE PAST?

Fewer people are dying from climate-related catastrophes than ever before, even though there are now a lot more people on the planet than ever before. Modern warning and response systems (such as emergency supplies to disaster-stricken areas) have greatly reduced human casualties.

42. DO MORE PEOPLE DIE FROM EXCESSIVE HEAT OR COLD?

More people die from excessive cold than from excessive heat every year. Adaptation over time has and will continue to moderate these effects, as will improved health systems commensurate with more wealth. Heat strokes will not become responsible for even as low a number as 0.0001% of human deaths.

43. IS CLIMATE CHANGE AN EXISTENTIAL PROBLEM FOR HUMANS OR HUMAN CIVILIZATION?

Climate change is not expected to become an existential problem for human civilization much less humanity. Calling it an existential threat to humanity is unscientific hyperbole.

In fact, one can go further. All mainstream models suggest that it is even unlikely that climate change will push either Earth’s population or economic growth into the negative. Human population growth and living standard growth will be positive. The negative effects of climate change will be small relative to the much larger natural positive growth due to economic and technological progress.

Of course, relative to a scenario in which there was no climate change at all (and thus no mitigation needed), worldwide growth will be a little lower.2 However, life will largely go on in most places (and as before). There will likely not even be a negative net economic effect of climate change in regions that are temperate, cooler, and wealthier today. Adaptation and migration will mitigate the negative effects of climate change in the hottest regions. Nevertheless, some harm will come to them.

44. WHY WORRY IF CLIMATE CHANGE IS NOT AN EXISTENTIAL THREAT?

Malaria is not an existential threat to humanity, and yet it still is terrible. World War II was not an existential threat, and yet it was still terrible. If humanity had had the ability to reduce it, we should have. Climate change need not be an existential threat to make it terrible; and humanity would be well advised to worry about it and to reduce its emissions.

45. WILL THE UNITED STATES AND OTHER RICH COUNTRIES FEEL DEVASTATING EFFECTS FROM CLIMATE CHANGE?

Rich countries will (very) likely not feel devastating effects of climate change. OECD countries are more than rich enough to ride it out. The expected increase in temperature may make New York feel more like DC — but this will not be the end of the world. (And one in seven households moves every year in the U.S., so over time, Americans will simply move towards where they want to live.) Furthermore, rich countries tend to lie in colder regions, where temperature rise may not even turn out to be economically harmful at all.

46. WILL POOR COUNTRIES FEEL DEVASTATING EFFECTS FROM CLIMATE CHANGE?

Poor countries will be more exposed to the harmful effects of climate change. This is for two reasons: First, poverty makes it more difficult to adapt. Second, many poor countries are already in areas that are quite hot. A little higher temperature could push them over the edge. Fortunately, temperature rises in poor countries around the equator have been less than in rich countries in Northern latitudes.

47. WHAT IS THE “TRIFECTA” OF CLIMATE SUFFERING?

1. A large population, exposing many inhabitants.
2. A hot climate, susceptible to going over the edge with just a few more degrees.
3. A poor region, where inhabitants don’t have the resources to insulate themselves against bad consequences.

When summed across the planet, this is where most of the global climate-change damages will occur. Namibia is not a big world problem, because few people live there. Singapore is not a problem, because it is rich. Mongolia is not a problem, because it isn’t overly hot there. Nigeria and Bangladesh are problems, because they are hot, poor, and full of millions of people who will suffer.

48. HAS AFRICA BEEN SUFFERING THE BRUNT OF CLIMATE CHANGE?

Africa has suffered relatively little temperature climate change yet. Climate change has been relatively more severe in higher latitudes (Northern Eurasia and Canada). However, being hotter and poorer, even Africa’s lesser climate change has translated into more economic harm in the second half of the twentieth century. Interestingly, this has not been the case since about the year 2000. That is, years in which temperature was higher were not years in which hot countries’ economies performed worse.

49. HOW QUICKLY CAN CURBING OF EMISSIONS REDUCE CLIMATE CHANGE? IS CURBING EMISSIONS AN EFFECTIVE WAY TO ADDRESS CLIMATE-CHANGE HARM?

The curbing of emissions could very slowly decelerate the warming of the planet — with great delay, on the order of many decades. As a measure to adapt to climate change by preventing or reducing it in the first place, emission curbs are extremely ineffective.

50. COULD EARTH BE COOLING IN THE FUTURE?

Earth could indeed be cooling in the future. A large asteroid impact or super-volcano outbreak could induce catastrophic cooling of the planet. (Earth has never been perfectly safe.) However, there is no evidence that cooling events are impending, at least as far as scientists can predict. Scientists expect dramatic warming, not cooling. Cooling could but is unlikely to happen.

51. IS CLIMATE CHANGE THE WORST ENVIRONMENTAL DISASTER BROUGHT ABOUT BY HUMANS?

It is arguable whether climate change is the worst environmental impact of humanity. Habitat loss, species extinction, ocean depletion, and biosphere destruction rank higher on my own “fear” meter. However, the fact that there are many other environmental problems does not reduce the seriousness of the climate-change problem.

Of course, some people even fear artificial intelligence (such as ChatGPT). I am more afraid of the long-term declining relative cost of weapons of mass destruction, nuclear war, and religious extremists.

52. ARE THERE OTHER SIMILARLY-LARGE THREATS TO HUMANITY?

There are no known reasonable-probability threats that are existential to humanity. However, there are some exceedingly unlikely potential threats that could be existential. Scientists have no good measures of their probabilities and thus much of this is speculation.

For non-existential but catastrophic scenarios, consider the following:

• Some people even fear artificial intelligence (such as ChatGPT). (I disagree.)
• I am more afraid of the long-term declining relative cost of weapons of mass destruction, nuclear war, and religious extremists.
• Supervolcanoes will erupt sooner or later (think every few dozen millenia), and will cause global cooling for a few years.
• The asteroid Apophis will pass by Earth in 2029 inside our human satellites. If it had just bent a little more inward, it would have had an impact our the same as all nuclear arsenals combined. Sooner or later, one of these will hit us.

53. WHAT REGIONS OF THE GLOBE HAVE GOTTEN HOTTER?

Over the last 50 years, virtually all regions of the globe have gotten hotter. The more northern latitudes (Europe, Scandinavia, Russia, Canada) have generally experienced more global warming than the more temperate and equatorial regions.

See also the map in Q 21.

54. WHERE WILL IT WARM MOST IN THE FUTURE? WHICH COUNTRIES WILL BE MOST HARMED? WHICH WILL NOT?

Science has not progressed enough to allow us to reliably forecast where it will warm more or less. Scientists are better at predicting the effect of greenhouse gases on overall planetary temperature than on specific regions. Earth is a very complex system with many weather phenomena (e.g., related to ocean circulation). It may well be a reasonable first estimate that most regions will experience roughly equal global warming or warming in line with existing trends.

55. WILL ALL COUNTRIES EXPERIENCE ECONOMIC HARM?

It is a reasonable conjecture that colder countries could benefit from increasing temperatures or at least be harmed less than more temperate and hotter countries.

56. WILL SIBERIA (RUSSIA) AND NORTHERN CANADA BENEFIT FROM GLOBAL WARMING?

Parts of Siberia and Northern Canada will become more temperature and suitable for human habitation. However, other areas further north will experience permafrost warming. The release of their “foul” frozen CO₂ and methane can render those regions uninhabitable for a few decades.

57. WILL THE SAHARA BECOME HOTTER?

It is likely that the Sahara will become hotter just as the rest of the planet is getting hotter. However, due to the complexity of Earth, scientists cannot predict with good certainty how specific regions of the globe will change. Moreover, the Sahara is already practically uninhabitable, so further warming of the Sahara matters relatively little to humans.

58. WILL THE SAHEL BECOME HOTTER?

Absent better predictions (that scientists cannot reliably provide), a reasonable presumption may well be that the Sahel will warm the same as the rest of the planet. Unlike the unpopulated Sahara, over 100 million people live in the Sahel.

59. ARE SCIENTISTS SURE THAT THE SAHEL WILL BECOME LESS INHABITABLE?

Scientists are not sure that the Sahel will become less inhabitable. Climate change could increase the rainfall in the Sahel. Scientists do not have models that are good enough to predict weather patterns over a century. Their best predictions are only that Earth overall will become warmer. If the Sahel remains as dry and if it becomes hotter, it will of course become less habitable.

60. WILL THE USA AND WESTERN EUROPE BECOME HOTTER?

Absent better predictions (that scientists cannot reliably provide), a reasonable presumption may well be that these countries will warm the same as the rest of the planet. (Changes in weather patterns and ocean circulation could, however, have dramatic effects.)

61. WHAT CAUSES SEA-LEVEL RISE?

The primary cause of rising sea level is the expansion of water as the global temperature is increasing. This is a small but steady process. It is slow, because the oceans hold a lot more heat than the atmosphere, especially in their lower layers. It may take many centuries or millennia for them to equilibrate to the atmospheric temperature. During this slow process, colder ocean temperatures help stabilize the warmer atmospheric temperature.

The secondary cause is the movement of ice sheets sliding from land into the oceans. This could suddenly accelerate.

62. HOW HAS THE SEA-LEVEL RISEN? WHAT IS THE FORECAST SEA-LEVEL RISE?

From a baseline of 1980, the IPCC predicts

Yes, the IPCC is aware of both thermal expansion and ice-sheet melting.

The IPCC most likely scenario predicts a global sea level rise of 40 cm (about 16 inches) by 2100 relative to 1980. About half has already occurred. Thus, by 2100, the sea is forecast to rise another 20-25 cm (about 8 inches) relative to today. However, the increase will likely continue for many centuries thereafter.

Interestingly, the IPCC does not predict an imminent collapse of the Greenland or West Antarctic ice sheets — because if they collapsed, their water could then flow from land into oceans and raise sea levels by a few feet. (The lack of expectation does not mean that it couldn’t happen.)

63. IS THE FORECAST SEA-LEVEL RISE UNPRECEDENTED?

The forecast sea-level rise of 20-40 cm over the next 100-200 years is very small compared to historical sea-level rises. Just 10,000 years ago, the ocean sea level was 6,000 cm (2,000 inches) lower than it is today.

64. HOW WILL THE ELEVATED SEA LEVEL BE HARMFUL?

The increased sea level will mean more flooding during extreme weather events (such as during storm surges, tropical cyclones, tsunamis, and perigean spring tides, which occur when the moon is either new or full and closest to Earth). There will also be serious effects on the salinity of their groundwater.

65. CAN REGIONS BELOW SEA LEVEL REMAIN HABITABLE?

Holland has shown the world centuries ago how to build dykes to allow below-sea-level regions to thrive. Note also that the relative costs of building these dykes were far higher centuries ago then than they would be today.

66. WILL COASTAL REGIONS SOON BE FLOODED? WILL LARGE SWATHES OF LAND IN FLORIDA, BANGLADESH, INDONESIA, ETC. SUBMERGE?

The projected further sea-level rise by 2100 is about 20-25cm (8 inches). This rise is not trivial, but it also is not the end of the world — even for most (but not all of) Florida, Bangladesh, and Indonesia. These regions will not sink below the ocean. The sea will not likely regularly flood large areas under ordinary circumstances, but will during storm surges.

67. WILL MANHATTAN SINK INTO THE OCEAN?

Manhattan will not sink into the ocean for many generations. More likely, New York will spend money on shoring up its seawalls in order to protect against rare flooding events (e.g., during hurricanes).

68. WILL FLORIDA AND NEW ORLEANS SINK INTO THE OCEAN?

Florida and New Orleans are more tenuous than Manhattan, if only because their areas are far larger. They can be saved by spending (lots of) money to protect them from seawater rise.

69. IS CLIMATE CHANGE AN EXISTENTIAL PROBLEM FOR MANHATTAN AND FLORIDA?

(Any changes can become existential problems for some people. This question is about existential problems for large parts of a population.)

The rising sea level will not become an existential problem for Manhattan, which is small enough to be easily protected by seawalls. Some parts of Florida may be lost if storm surge protection becomes too expensive.

70. IS CLIMATE CHANGE AN EXISTENTIAL PROBLEM FOR PEOPLE IN LOW-LYING COUNTRIES LIKE INDONESIA AND BANGLADESH?

(Any changes can become existential problems for some people. This question is about existential problems for large parts of a population.)

The rising sea level can become an existential problem when people are poor and do not have the resources to adapt to the negative effects of climate change. Wealthier people and nations can adapt, move, or buy technology that reduces the harmful effects of climate change. However, the most important problem for most Indonesians and Bangladeshis is not the increased sea level (of 8 inches) in 100 years — it is their poverty today and in the near future.

71. CAN EMISSION CURBS HELP PROTECT AGAINST SEA-LEVEL RISE IN FLORIDA, NEW ORLEANS, AND MANHATTAN?

Emission curbs in the United States or worldwide cannot help protect low-lying areas against sea-level rise. This is because even if the United States or even the world could cut all its emissions immediately, the rate of sea-level rise in Florida, New Orleans, and Manhattan would not change for many centuries. This train has left the station long ago. The only protective devices against sea-level rise are barriers.

72. DO WE OWE OUR DECENDENTS TO LEAVE THE PLANET HOW WE RECEIVED IT?

Absolutely not. It would have been atrocious if our ancestors had done this to us. As little as 200 years ago, most people lived in constant poverty and hunger. Famines killed millions of people every year. Life expectancy was 30-50 years. Humanity did not live in the equivalent of today’s Sweden, and it took some pollution to get us to where we are today.

Even today, the average person does not live in Sweden and the ambition to improve worldwide living standards is not about plastic bags and SUVs. It is about offering the billions of poor people the same living standards that most readers of this book already enjoy.

I hope that we will leave this planet in good shape for our decendents (and their ecosystems) to enjoy higher standards of living than we enjoy today. As humanity becomes wealthier, it will hopefully take better care of the environment.

Incidentally, contrary to Greenpeace’s perspectives, most environmental devastation was not brought about by industrialization or capitalism. It was brought about by the population explosion. If the world had only 1 billion inhabitants, as it did in the early 19th Century, then pollution, ecosystem ravaging, and global warming would not be major global problems. To bring us back to nature and where we were just 200 years ago would therefore not require the elimination of industry, it would require the elimination of 7 billion people. This is a choice that is not palatable. It is a Rubicon that humanity has already crossed.

73. WHERE ARE ALL THE PEOPLE OF THE WORLD?

Contrary to ethnocentric Western perceptions, the human population concentrates heavily in Africa, India, and Asia. The following image helps visualize this observation:

74. HOW HAS THE WORLD POPULATION GROWN? HOW WILL IT GROW?

In billions of people:

75. HOW CAN POPULATION GROWTH PLAY BE SLOWED DOWN?

The most effective way seems to be to give women more rights, especially in “traditional” societies in poorer regions where womens’ rights are often reprehensibly bad. More womens’ rights tends to lead to lower birth rates, a “demographic dividend,” higher incomes, and an escape from the so-called Malthusian trap.

76. WHAT PART OF INCREASED EMISSIONS CAN BE ATTRIBUTED TO POPULATION GROWTH AND WHAT PART TO INCREASED PER-CAPITA CONSUMPTION?

The part of increased emissions that can be attributed to population growth rather than to increased per-capita consumption depends on the region.

OECD: No increasing emissions: No population growth. Shrinking per-capita consumption.

Around 1990, the OECD with its 800 million people emitted about 15 GtCO₂ GHG out of about 30 GtCO₂ worldwide. Around 2020, 1,400 million people in the OECD still emitted about 15 GtCO₂ of about 50 GtCO₂. Thus, the OECD has reduced its per-capita consumption. The same is true for the USA. Around 1960, about 180 million Americans emitted about 3 GtCO₂. Around 2020, about 330 million Americans emitted about 5 GtCO₂. Thus, all U.S. emissions growth was due to population growth, not to increased per-capita consumption.

Non-OECD: Increasing emissions: Increasing population. Strongly increasing per-capita consumption.

Most of the world’s increased per-capita consumption occurred in Asia where countries became wealthier. China was the development success story of the last 30 years, showing how a country could climb out of poverty. In 1960, China’s 700 million people emitted almost no CO₂. In 2020, China’s 1.2 billion people emitted about 10 GtCO₂. Thus, most of its emissions increase was due to increased per-capita consumption. In 1960, India’s 450 million emitted 0.1 GtCO₂. In 2020, India’s 1.4 billion people emitted 2 GtCO₂. Again, most of its emissions increase was due to per-capita increased consumption.

Worldwide: Increasing emissions. Increasing population. Increasing per-capita consumption.

The picture is an amalgam of OECD and non-OECD countries. Around 1960, about 3 billion people emitted about 10 GtCO₂. Around 2020, about 8 billion people emitted about 35 GtCO₂. Thus, about half of the world’s emission growth was due to population growth, and about half was due to increased per-capita consumption.

Most impending consumption increases over the next 50 years will be due to increased per-capita consumption in countries seeking to copy China’s wealth increase — principally, but not only, in Asia. Most impending population growth will occur in Africa. Its contribution to increased emissions will be small, however, because Africa does and is expected to consume very little energy.

77. HAVE CAPITALISM AND INDUSTRY CAUSED AFRICA’S POVERTY?

Capitalism and industry have almost surely not caused Africa’s poverty. If anything, Africa is the least capitalist and modern region of the world. The only countries that have escaped abject poverty over the last 60 years are those that have adopted capitalism, modernism, and industry (such as China, Singapore, Chile, and some former Eastern European countries).

All other attempted solutions have failed. No country has ever escaped poverty by the grace of the United Nations donation box. Utopian unproven solutions are like playing with fire.

Although Western and other companies have been mining resources in many countries in Africa, this has not lowered the incomes of the affected African countries. Moreover, much of the resulting harm from mining is due to local corruption, tribalism, and nepotism rather than the resource extraction itself. In contrast to capitalism and the resource extraction of Western companies, other factors have contributed more to Africa’s predicament. The obvious are past colonialism, imperialism, and slavery as well as pervasive and persistent tribalism and gender and economic inequality.

Advocacy groups sometimes forget that Africa was never a utopia. For thousands of years, life in Africa has been hard, droughts and hunger common, diseases rampant, life expectancy short, education minimal, and tribal wars raging.

78. HAVE CAPITALISM AND INDUSTRY CONTRIBUTED TO AFRICA’S POVERTY?

The primary cause by which modernism seems to have contributed to making Africa today worse off is not capitalism. Instead, modern health, hygiene, transportation, and emergency aid have made it possible for the continent to rapidly grow its population. Africa hosted 0.2 billion people in 1960. Today, Africa hosts 1.3 billion. By the end of the century, it will host 4 billion.

No country has ever climbed out of poverty while sustaining such high population growth rates. Poverty will only come down after birth rates will have declined. The continent remains poor and already has barely enough resources to feed and improve the lives of its people. Given the chance to emigrate, few Africans decline. Climate change will make Africa’s situation worse, but climate change is not the primary root cause of Africa’s poverty.

The problems are obvious. Effective solutions are not. It is a depressing situation for humanitarians.

79. WHAT ROLE DOES GENDER PLAY IN (FIGHTING) CLIMATE CHANGE?

Harm from climate change is not gender-specific. However, in most regions of the globe, the empowerment of women has led to lower birth rates. This change, in turn, has reduced poverty and ultimately lowered total emissions growth (although increased wealth has also at first increased per-capita and thus total emissions).

80. WHAT ROLE DO COLOR AND CULTURE PLAY IN (FIGHTING) CLIMATE CHANGE?

Climate-change needs to be tackled by people of many colors and cultures if it is to be effective. Harm from climate change is not skin-color- or culture-specific. However, people of color are on average poorer than white people. This means that they will likely incur more harm from climate change. (Wealth is always an effective buffer against adverse developments.)

On the other hand, poorer people are also often more concerned about their current poverty than they are about future poverty and climate change, which will take 30-60 years to materialize (when they will hopefully also be wealthier than they are today).

81. WHY DO ENERGY AND FOSSIL FUELS DESERVE SO MUCH ATTENTION IN THE FIGHT AGAINST GREENHOUSE GASES AND CLIMATE CHANGE?

For the most part, fossil-fuel use has been directly responsible for the increase in GHGs in the atmosphere. Energy deserves so much attention because about 75% of world CO₂ emissions come from the burning of fossil fuels. Another 20% is due to agriculture. All other sources of anthropogenic greenhouse gas emissions are secondary.

82. WHAT IS THE BASIC UNIT OF ENERGY USE?

Energy is power applied for a certain amount of time. There are many measures of energy such as BTU, Joule, Therms, barrels of oil, quads, and so on. The most logical one is from the metric system: One basic unit of energy is the Watt-hour (Wh). A Petawatt-hour (PWh) is a quadrillion Wh; a terawatt-hour is a trillion Wh; a gigawatt-hour is a billion Wh; and a megawatt-hour is a million Wh. For planet-wide calculations, we usually work with Petawatt-hours (PWh). World primary energy consumption is just under 200 PWh per year. A large nuclear power plant can generate a few Terawatt-hours (TWh) per year, enough for a modern city of about 200,000 people.

83. HOW IS MOST ENERGY GENERATED THESE DAYS?

About 90% of the world’s energy is from dirty fuels (about 80% fossil fuels).

84. WILL CLEAN POWER REPLACE FOSSIL FUELS?

Eventually, yes. In this generation, no.

As of 2022, about 80% of the world’s energy is still supplied by fossil fuels. In fact, in absolute terms, the world’s fossil fuel use is still increasing faster than the world’s clean energy use. (This is no longer the case in OECD countries. In fact, in many OECD countries few, if any, new fossil-fuel plants are being built today.) Even so, the use of coal is still growing.

The question now is whether clean energy can largely displace fossil fuels by the second half of this century or by the middle of the next century. This outcome will depend mostly on whether the clean-energy storage cost problem (explained below) can be solved.

85. WHAT IS THE DIFFERENCE BETWEEN NATURAL GAS, NATGAS, AND METHANE

NatGas is an abbreviation for Natural Gas. It consists primarily of Methane (CH₄). Though not exactly correct, the terms are often used interchangeably.

86. IS NATURAL GAS “CLEANER” THAN COAL?

NatGas is cleaner at the final point of use. Unfortunately, NatGas leaks left and right all along the extraction and transmission paths. Taking these leakages into account, and the higher greenhouse gas potential of Methane, it is not clear that NatGas is any cleaner than coal from a GHG perspective.

87. ARE CHEAP FOSSIL FUELS ABOUT TO RUN OUT?

Cheap fossil fuels are neither about to run out nor about to bump up against their natural availability limits for decades. Plenty of cheap fossil fuels remain in the ground that can profitably be extracted at today’s prices. Some estimates suggest another 50 years for gas and oil, and another 100 years for coal.

Depending on the price at which they can be sold, fossil fuels could be retired sooner or later. When demand prices turn higher than extraction and supply costs, energy companies could explore new and other sources — including even manufacturing them from thin air (with other energy) if need be.

88. WHAT IS THE BASIC UNIT OF GREENHOUSE GAS EMISSIONS?

The standard unit of greenhouse gas emissions is the “metric tonne of CO₂” (tCO₂) — roughly the effect of burning a 1-foot cube of pure graphite coal (C). One “gigatonne of CO₂” (GtCO₂) is 1 billion tonnes — roughly the effect of burning a 1,000-foot cube of coal (C). Humanity burns the equivalent of about a 3,000-foot cube of coal (one cubic kilometer) every year. (Earth has an area of about 510 million square kilometers.)

89. HOW MANY TONNES OF CARBON-DIOXIDE DOES THE AVERAGE PERSON EMIT PER YEAR?

90. ARE HUMANS RESPONSIBLE FOR INCREASED LEVELS OF GREENHOUSE GASES (GHG) IN THE ATMOSPHERE?

Humans have almost surely been wholly responsible for increased levels of CO₂ in the atmosphere over the last 200 years. Scientists know this both from the isotopes of CO₂ in the air, and from the fact that we can compare the total increase in atmospheric CO₂ to the total amount of extra CO₂ that humanity has emitted.

91. ARE THERE (NOT) ALSO NON-ANTHROPOGENIC SOURCES OF GREENHOUSE GASES?

There are many other non-man-made sources of greenhouse gas emissions. However, they have remained roughly stable for thousands of years, and their annual inflows just about match their annual outflows. Only human emissions have increased greatly over the last 200 years with the industrial revolution and population growth.

92. WHAT ACTIVITIES EMIT WHAT GHGS?

93. WHY DO SOME PUBLICATIONS CLAIM THAT HUMANS EMIT 35 GTCO₂ WHILE OTHERS CLAIM 55 GTCO₂?

Different publications report different things, so it is important to read the fine print. Aside from the usual uncertainties in measuring emissions (and attributing them to specific emitters), publications often report one of the following: The lowest measure of about 35 GtCO₂ per annum are purely CO₂ emissions (about 38 GtCO₂ per annum in 2022). Other long-lived greenhouse gases are often measured in terms of “CO₂ equivalent.” Methane is a shorter-lived greenhouse gas, which adds about 10 GtCO₂. Nitrogen- and Fluor-based gases add another 5 GtCO₂. The largest number of about 55 GtCO₂ also adds a land charge (also about 5 GtCO₂), because humanity has reduced the CO₂ absorption capabilities of the biosphere principally by converting forests into fields. (On occasion, even lower numbers are sometimes quoted if consideration is given only to energy-related emissions or to electricity-related emissions.)

94. DOES THE PLANET SCRUB (ANTHROPOGENIC) GREENHOUSE GASES FROM THE ATMOSPHERE?

Yes, the planet scrubs a lot of GHGs (including the most important CO₂). However, over timespans of centuries, natural planetary geological processes cannot scrub all anthropogenic CO₂ emissions. The following is an over-simplification, but it will do. About half of anthropogenic CO₂ is scrubbed by the planet in the same year as it is omitted (half into the ocean, half into weathering of stones). Another half of the remaining half will be scrubbed within the 30 years thereafter. And the rest will stay in the atmosphere for thousands of years. Eventually, in a few thousand years, Earth will likely return to an equilibrium similar to that prevailing for the last 50 million years. (If you can wait it out this long, increased CO₂ will not be a concern.)

Therefore, because the planet is no longer capable of scrapping all emissions in human-life time frames, anthropogenic CO₂ has been accumulating in the atmosphere, from about 280 ppm to about 420 ppm over the last two centuries.

95. WILL EARTH CONTINUE TO BE ABLE TO SCRUB GREENHOUSE GASES AT THE SAME RATE?

Scientists have not detected a notable change in Earth’s ability to scrub CO₂. However, they are not certain whether Earth will be able to scrub more or less CO₂ in the future than it does today.

96. WHEN DID ANTHROPOGENIC GREENHOUSE GAS EMISSIONS BECOME BIG ENOUGH TO BE A GLOBAL PROBLEM?

Atmospheric CO₂ levels in the atmosphere turned into a global climate problem around the middle of the 20th century. Although CO₂ levels themselves already started increasing modestly after around 1900, as late as 1965, humanity still consumed only about 50 PWh of primary energy. Today, humanity consumes nearly 190 PWh. By 2050, it will consume nearly 250 PWh. The rate at which humanity has been emitting has been accelerating. If humanity had stayed at its 1965 emission levels, global emissions would now be running at only about 20% of their actual current levels. At this low a level, clean-energy progress could probably have reduced the speed of global warming to the point where increasing global temperatures would have remained a secondary environmental concern.

97. WHY IS STONE WEATHERING NOT REMOVING THE CARBON DIOXIDE?

The weathering of minerals — especially Olivine, the most abundant mineral on Earth — is indeed removing anthropogenic CO₂. There are more than enough weathering minerals to remove all the human CO₂ many times over. Unfortunately, the speed of the process is limited by their exposed surface area. There are proposals to speed up the natural sequestration process by grinding up minerals, especially near the ocean. Unfortunately, such an undertaking would be very expensive.

98. ISN’T ANTHROPOGENIC CARBON DIOXIDE SMALL IN THE SCHEME OF PLANETARY RESERVOIRS?

Anthropogenic emissions of about 50 GtCO₂ per year may seem small when compared to the CO₂ held by the oceans (which hold about 140,000 GtCO₂); and even atmosphere, permafrost, and biosphere (which hold about another 3,000-5,000 GtCO₂ each). Any one year’s anthropogenic contribution is indeed small. However, over the last century, humanity has added an extra 1,000 GtCO₂ to the atmosphere — and this is more than enough to cause global warming.

99. WHAT ROLE DO VOLCANOES PLAY?

Volcanoes have played a role in global warming and cooling since forever. However, over the last century, the increasing CO₂ concentration in the atmosphere and the resulting global warming have had nothing to do with volcanoes. They have been entirely anthropogenic. (And it would matter little if volcanoes had been responsible. The key problem of how to deal with increasing global temperature would remain the same.)

There are super-volcanoes, whose outbreaks could significantly alter the planetary balance. They can emit the equivalent of multiple years of human CO₂. However, the last such outbreak occurred in New Zealand about 25,000 years ago. Even more worrisome outbreaks — such as Yellowstone’s outbreak — last occurred about 500,000 years ago. Scientists cannot predict when the next such outbreak will occur.

100. HOW HAS THE CURRENT CARBON-DIOXIDE CONCENTRATION IN THE ATMOSPHERE INCREASED?

The natural pre-industrial concentration of CO₂ in the atmosphere was about 280 ppm. It is about 410 ppm as of 2022, currently growing at a rate of about 2.2 ppm per year. If we counted in the concentration of other greenhouse gases, the equivalent number would be more like 500 ppm.

101. HOW MANY EXTRA GIGATONNES OF CARBON DIOXIDE HAVE HUMANS ADDED TO THE ATMOSPHERE?

The extra 110 ppm of atmospheric CO₂ represent an additional 1,000 GtCO₂ in the atmosphere that have been added by humans. They are based on total worldwide emissions of about 1,700 GtCO₂ since 1800, of which 700 GtCO₂ has already been scrubbed by the planet.

102. IS EARTH IN A CARBON-DIOXIDE DROUGHT?

For all practical purposes, Earth is not in a CO₂ drought — that is, Earth is not in a drought relative to the last 50 million years — i.e., the environment in which modern mammals have evolved. For the most part, this is all that should be relevant.

It is, however, true that Earth now has much less CO₂ in the atmosphere than it used to have during the age of the dinosaurs; and that many of today’s plants would still grow better in an atmosphere with more CO₂. In this sense, CO₂ is indeed more constrained than it used to be.

103. WILL MORE CARBON DIOXIDE IN THE ATMOSPHERE MAKE BREATHING MORE DIFFICULT?

CO₂ is a global gas that diffuses well. Global CO₂ levels outdoors are forecast to be more like how they are today in human dwellings than how they are outdoors. (It could have an effect on high-level athletic performance.)

Increased global CO₂ in the atmosphere will not make breathing more difficult. Other pollution in the atmosphere is considerably more toxic. The worst pollution comes from fossil fuels and in the form of small particle emissions. Their effects are more local (and lethal) than the effects of CO₂. (In some places like India, agricultural small particle emissions are also exceedingly deadly.)

104. WHAT ARE THE LEVERS DRIVING EMISSIONS?

The IPAT identity shows that

• The number of people can change.
• The per-capita emission can change

This is not a theory but an identity, because “People * Emissions/People” is Emissions. It cannot have left out anything.

Decomposing this further,

• The number of people can change.
• The per-GDP emission can change
• The GDP may change.

The Kaya identity (named after Japanese economist Yoichi Kaya) expands this to energy:

• The number of people can change.
• The per-capita consumption of energy can change (e.g., driving and flying less; economic recessions).
• Energy efficiency can change (e.g., insulating better).
• Emissions efficiency can change (e.g., using clean energy).

All efforts to change emissions have to work through one or more of these mechanisms.

105. HAS THE WORLD IMPROVED ITS ENERGY AND EMISSIONS EFFICIENCY?

Yes, the world has increased both its energy efficiency and its emissions efficiency. However, the efficiency improvements have been too small to stabilize world emissions. THis is because the emissions from the increasing number of people and the increasing per-capita energy consumption in developing non-OECD countries have been growing too fast.

Roughly speaking, emissions per person have been constant for about 50 years. World emissions have thus been growing in line with world population.

106. HAS ACTIVISM REDUCED GLOBAL EMISSIONS GROWTH, ATMOSPHERIC GREENHOUSE GAS CONCENTRATIONS, AND GLOBAL WARMING?

It seems unlikely that the fight against climate change has meaningfully reduced global emissions growth. There has been no discernible dent in worldwide energy use or emissions that has been associated with any climate-change-related concerns or regulations.

For example, after groundbreaking testimony by NASA scientists about the effects of global warming, energy consumption and greenhouse gas emissions have climbed as strongly as they did before. However, although the evidence suggests that activism was not highly effective, there could have been some effect — merely too small to be detectable with common econometric tools or one reducing emissions growth from what would have been even worse.

107. ARE THE OCEANS ACIDIC?

The oceans are not acidic but alkaline.

108. ARE THE OCEANS ACIDIFYING?

The oceans are acidifying (becoming less alkaline), because CO₂ from the atmosphere has been dissolving into the oceans, turning into carbonic acid.

109. IS CARBONIC ACID IN THE OCEAN TOXIC?

Ocean acidification is not in itself directly toxic to most marine organisms. There are however indirect effects, primarily related to the calcium concentration in the ocean. See the next question.

110. IS OCEAN ACIDIFICATION HARMFUL?

Acidification triggers an indirect harmful effect. Many organisms in the ocean, especially certain plankton, use calcium (chalk) dissolved in the ocean to build their shells. This calcium is now instead binding with the additional dissolved CO₂. (The calcium thereby neutralizes the carbonic acid and pushes the ocean back towards more alkalinity.) However, this also means that this calcium is now no longer available to shell-building organisms.

Fortunately, the oceans have access to more than enough calcium to bind all anthropogenic CO₂ many times over. Unfortunately, it takes time for more calcium to dissolve into the water. For many shell-building organisms, the (temporarily) reduced calcium availability in the ocean will cause extinction. This can have knock-on effects further down the food chain.

There are proposals to speed up the natural calcium dissolution process by adding lime (calcium) from ships. Unfortunately, such an undertaking would be very expensive.

Sidenote: Although acidification is harmful to the ocean biosphere, its effects are less severe than the aggressive unlimited overfishing undertaken by humans. With billions of people in the developing world becoming richer and more eager for tasty seafood, our raping of the oceans is only likely to get worse. This situation is desperate. And, no, your eating less Sushi will not save the world’s fish stocks, either.

111. WHAT FRACTION OF THE WORLD LIVES IN RICHER COUNTRIES?

As of 2020, about 20% of the world’s population lives in OECD countries, 80% in non-OECD countries.

See also Q 74.

112. WHAT FRACTION OF WORLD GDP IS PRODUCED IN RICHER COUNTRIES?

There are some difficulties comparing the purchasing power of outputs in different countries, but a reasonable approximation is that OECD countries produce about 45% of the world’s economic output. In trillion of dollars:

The OECD is forecast to enjoy moderate growth in its output and living standards, while China, India, and South-East Asia are forecast to experience stronger growth. Thus, the OECD’s relative share of world output is and will be declining.

113. HOW IS ENERGY USE GROWING IN RICH VS. POOR COUNTRIES?

Annual energy use in Peta-Watt hours is expected to grow as follows:

Most energy use growth will occur in non-OECD countries.

114. HOW ARE TOTAL HUMAN CARBON DIOXIDE AND GREENHOUSE GAS EMISSIONS GROWING IN RICH VS. POOR COUNTRIES?

Total Annual Emissions In Gigatonnes (Gt) of CO₂:

Adding in other GHGs (like Methane) would increase these estimates by about 50%.

115. DO THE USA, EUROPE, OR CHINA EMIT MORE CARBON-DIOXIDE PER CAPITA NOWADAYS?

The average American emits about 14 tCO₂/year (tonnes of carbon dioxide per year); the average European 6.4 tCO₂/year; the average Chinese 7.6 tCO₂/year. (And there are, of course, far more Chinese than there are Americans and Europeans together.) The average Indian and other Asians emit about 2 tCO₂/year.

See also Q 89.

116. HAVE RICHER OR POORER COUNTRIES EMITTED MORE CARBON-DIOXIDE OVER THEIR LIFETIMES?

As of 2020, over the last two centuries, in cumulative terms:

• OECD countries have emitted about twice as much CO₂ as non-OECD countries. The single-largest cumulative emitter has been the United States.
• By mid-century, non-OECD countries collectively will have caught up. (China will also have emitted as much as the United States.)
• By the end of the century, non-OECD countries will have easily overtaken OECD countries; China will have emitted far more than the United States.

117. ARE RICHER COUNTRIES OR POORER COUNTRIES EMITTING MORE CARBON-DIOXIDE NOWADAYS?

Poor countries (non-OECD) emit about twice as much CO₂ today as rich countries (OECD). (This statement should not be interpreted as a judgment about what share of emissions poor countries should be entitled to. It is a simple statement of fact.)

On a per-capita basis, inhabitants of the OECD consume, produce, and emit about twice as much as those outside the OECD. But the OECD contains under 20% of the world’s population. Therefore, the OECD is now responsible for just under 40% of the Earth’s energy consumption and under 30% of the world’s greenhouse gas emissions. The remainder is from non-OECD countries: their 80% of the world’s population consumes about 60% of its energy and emits about 70% of its greenhouse gases.

118. ARE RICHER COUNTRIES OR POORER COUNTRIES INCREASING THEIR CARBON-DIOXIDE EMISSIONS MORE NOWADAYS?

OECD countries have not increased their total emissions in over five decades. All increases in global emissions have come and will continue to come from non-OECD countries. By 2050, the rest of the Asian continent sans China will increase total world emissions by about 20% relative to today’s emissions. (As noted previously, this statement should not be interpreted as a judgment about what share of emissions less-developed countries should be entitled to. It is a simple statement of fact.)

119. WHICH COUNTRIES HAVE THE LOWEST AND HIGHEST ENERGY AND EMISSION EFFICIENCIES?

European countries have the best efficiency. China has the worst efficiency. It can be argued that this is due to a different activity and production mix. (China specializes in manufacturing for exports.) It is not clear that the same products could have been produced with lower emissions in Europe. However, it is also true that China has been feeding its industries disproportionately with coal, one of the dirtiest fuels in the world.

120. HAVE COUNTRIES CONSUMED MORE ENERGY (AND EMITTED MORE GREENHOUSE GASES) AS THEY HAVE BECOME WEALTHIER?

Countries have indeed consumed more energy and emitted more greenhouse gases as they have become wealthier. This is likely to continue.

However, the relationship has not been linear. Countries at first needed a lot of extra energy to climb out of abject poverty. Eventually, at much higher levels of development, the relationship between emissions and wealth flattened out. For example, the relatively-richer European countries now emit less CO₂ per capita than the relatively-poorer China.

121. HAS INCREASED LUXURY ENERGY CONSUMPTION AND GREED CAUSED THE INCREASE IN GREENHOUSE GAS EMISSIONS?

It partly depends on what one considers to be “luxury.” I consider the ability to drive to a store and transport goods and people, to heat and cool a house, to receive an education, to have a job in modern industry with safety and other standards or in an office, to have clean water, sanitation, and modern medicine, to be fed even in hard times, and to live long lives not as unnecessary greed and luxury.

By this definition, increasing greed and luxury in rich OECD countries have almost surely not been responsible for the large increase in emissions. If anything, the population in rich countries now emits less CO₂ per capita than it has for more than half a century, yet it has also greatly increased its (luxury) consumption.

By the same definition, increasing greed and luxury in poor non-OECD countries have almost surely not been responsible for the large increase in emissions, either. Their inhabitants consume less than those in OECD countries.

Almost all of the four-fold increase in energy consumption and emissions (which is still increasing) has come from poorer non-OECD countries, striving to escape poverty. (The most important and successful country has been China.) Today, non-OECD (poorer) countries already emit 2/3 of world CO₂ emissions (116 PWh out of 187 PWh). This proportion will grow to 3/4 within a generation (30 years). Most increase in energy consumption and emissions will continue to come from non-OECD countries — foremost, India and South-East Asia. Poorer countries do not want to wallow in luxury, plastic straws, and far-flung vacations. Instead, they primarily need more energy in their quests to escape widespread poverty — something that no one should fault them for.

122. COULD LESS LUXURY ENERGY CONSUMPTION REDUCE GLOBAL WARMING?

Although reductions always help, the effects of reduced luxury consumption on global emissions (and thus eventually on atmospheric CO₂ and eventually global temperature) would be small. The ever-increasing world energy consumption has not been primarily about more plastic straws, plastic bottles, needlessly running Hummer cars, far-flung vacations, and conspicuous consumption. Instead, it has been primarily about building and maintaining transportation, industries, universities, healthcare, agriculture, etc. — all necessary aspects of a modern economy and lifestyle.

123. COULD OECD COUNTRIES “JUST SAY NO” TO FOSSIL FUELS?

OECD countries cannot yet “just say no” to fossil fuels. Clean energy technology is not yet technologically fully ready and in wide enough abundance to take over. If fossil fuels were to be curtailed too hastily, it would cause a worldwide depression — the likes of which humanity has never seen before. Though initiated in the OECD, it would likely cost the lives of millions of people in poorer countries. It is also exceedingly unlikely that the public would have the political will to carry through with Draconian moves. (The 2022 experience also illustrates how even trivially minor energy hiccups can quickly lead to widespread panic.)

124. WOULD GLOBAL WARMING STOP IF ALL COUNTRIES GOT OFF THE FOSSIL-FUEL WAGON?

It is impossible for countries to “Get Off the Fossil-Fuel Wagon” for many decades. But even if a miracle made this possible without a concomitant worldwide economic depression, the already-present CO₂ in the atmosphere would still be enough to induce global warming to continue for at least one more human generation (about 30 years).

However, global warming would level off at a maximum temperature increase much lower than what experts now expect. Eventually, global warming would stop and reverse.

125. COULD “BELT-TIGHTENING” (LESS CONSUMPTION AND RECESSIONS) IN OECD COUNTRIES STOP GLOBAL WARMING?

Belt tightening in OECD countries cannot stop global warming in this century. Even if OECD countries could reduce or eliminate their entire fossil fuel use and achieve 100% clean energy (and they cannot for at least one more generation), world energy consumption and emissions would still not fall. (Of course, this does not mean that meaningful reductions in OECD emissions would not be a helpful contribution to reducing emissions, atmospheric GHGs, and global warming. The point is that belt-tightening in OECD countries would be a rather limited contribution.)

However, the world is so highly connected that an economic depression in OECD countries would almost certainly have devastating consequences for non-OECD countries. The resulting recession (and deaths) in non-OECD countries could also reduce their energy consumption and emissions.

126. WILL OECD COUNTRIES VOLUNTARILY REDUCE THEIR GREENHOUSE-GAS EMISSIONS?

There are indications that richer OECD countries are taking active measures to reduce their greenhouse gas emissions even when this is not in their interest — up to a point. For example, the point came when Germany was restarting its coal plants in 2022 in order to avoid an economic recession caused by reductions in NatGas availability and higher energy prices.

OECD countries will likely voluntarily further reduce their emissions primarily as clean energy becomes cheaper. Some political pressure may further reduce their emissions, though only modestly so. OECD countries may also “involuntarily” reduce their emissions if they fall into economic recessions.

127. COULD “BELT-TIGHTENING” IN NON-OECD COUNTRIES STOP EMISSIONS GROWTH?

Belt tightening in OECD countries cannot stop global warming in this century. The belt is already very tight. The per-person energy consumption is an (abject poverty-level) 5 KWh per day on the Sub-Saharan continent; 23 KWh on the Indian subcontinent; 90 KWh in China; 110 KWh in Europe; and 230 KWh in the United States and Canada. Africa, India, etc., will not be able to escape poverty without providing their people with far more energy — for physical labor, agriculture, transportation, industry, education, etc.

128. WILL NON-OECD COUNTRIES VOLUNTARILY REDUCE THEIR GREENHOUSE-GAS EMISSIONS?

In this century, non-OECD countries will consume more energy as they climb out of poverty. These countries will not give up the aspirations of their people for better lives. (However, success is not certain, because they could encounter long protracted economic depressions.)

Under expected economic growth and technological progress (i.e., cheaper clean energy), non-OECD countries will not reduce their total emissions. However, cheaper clean energy can reduce their emissions growths. Emissions could fall if clean energy costs drop even faster than expected.

129. WHAT IS THE “ECONOMIC APPROACH” TO ANALYZING PROBLEMS?

The approach of economics is to weigh costs and benefits when considering actions. It differs from an activist approach, which tends to focus only on one side. For example, Greenpeace often highlights the (very real) costs of climate change, but it rarely highlights the costs of fighting this climate change or the benefits in other locations. Similarly, energy companies often highlight the benefits of fossil fuels but not their climate-change consequences and very severe health costs.

In this FAQ, I take the economics approach, not the activist approach.

130. HOW DO ECONOMISTS DIFFER FROM OTHER (SOCIAL) SCIENTISTS?

Economists differ from other social scientists in the following respects:

• Economists generally believe that people are primarily self-interested, especially beyond friend-and-family groups. They are not intrinsically altruistic, especially when doing so is expensive and beneficiaries are not close friends and family.
• Economists generally believe that one should not compare current problems vis-a-vis Utopian ideal interventions but vis-a-vis realistic interventions. Economists generally have more relative faith in the inventiveness of people and less relative faith in real governments.
  
• Economists are more optimistic about the future of economies. It is often easier to see the harm of changes (e.g., loss of jobs) than it is to see the benefits (e.g., new jobs).

Other (social) scientists consider economists to be more cynical than themselves — and rightly so. Economists consider themselves more realistic and other social scientists as Panglossian.

131. WHERE DO OPINIONS (AND IDEOLOGY) DIVIDE ECONOMISTS?

Economists differ primarily in their opinions about how inefficient, costly, and political many real-world government interventions are likely to be. Other social scientists (like sociologists) tend to believe in more benevolent governments.

Thus, economists often agree with one another and other scientists on particular problems (such as climate change), although many economists may believe that government intervention is still not advisable. Other economists may believe that government intervention is unavoidable and necessary.

132. SHOULD YOU TRUST ECONOMISTS?

You should learn from the expertise and assessment of scientists, but you should not blindly trust any scientists. This caution applies to economists just as to all other scientists. Moreover, as in any other science, there are some more dogmatic and some more pragmatic economists. Again, you should carefully listen to the evidence and the arguments, and then you should make up your own mind.

The approach in my FAQ is generally mostly pragmatic.

133. DOES ECONOMICS RECOMMEND LAISSEZ-FAIRE (“LET THE MARKET RULE”) FOR GREENHOUSE GAS EMISSIONS?

Economics only recommends laissez-faire on principle when there are no “externalities” (i.e., costs imposed on others that are not parties to the decision). In the case of pollution, economics strongly recommends against laissez-faire.

134. WHAT IS ECONOMISTS’ STANDARD ECONOMIC RECOMMENDATION TO CURB GREENHOUSE GAS EMISSIONS?

The standard economic recommendation is a tax on GHG emissions. This tax would ideally be global to prevent companies and industries from escaping this taxation by relocating elsewhere.

135. WHAT IS THE MEANING OF THE SOCIAL COST OF CARBON (“SCC”)?

In economic terms, the social cost of carbon (SCC) is the social harm caused when one extra tonne of CO₂ is emitted. With some extra assumptions, it is also the prescription for the best level of tax that should be imposed on CO₂ emissions. (An upper bound on the SCC is the cost of removing the extra tonne of CO₂ from the atmosphere.) In practical terms, this is what economists often recommend as the best tax.

Agreeing on a tax on CO₂ in international treaties would also make for easier negotiation — instead of negotiations about who should rightly be allowed to emit what.

136. WHY IS IT CALLED THE ‘SOCIAL COST OF CARBON’ AND NOT THE ‘SOCIAL COST OF CARBON DIOXIDE’?

Unfortunately, the term “social cost of carbon” usually refers to the social cost of carbon dioxide and thus should be called that. Unfortunately, it has become common to call it the “social cost of carbon” instead. It is a common assumption that most people (you!) are aware of this misnomer. See also Q 136.

137. WHAT SHOULD THE SCC TAX BE?

Many economists peg the SCC at around $30-$50 per tCO₂ today, rising predictably every year after.

138. WHAT WOULD BE THE EFFECT / MEANING OF A $30-$50 TAX PER TONNE OF CARBON DIOXIDE?

In the United States, a $30-$50/tCO₂ tax would increase the cost of gasoline and natural gas by about 50-100%. Instead of $4/gallon, gasoline would cost about $6-$8/gallon. As has been shown by the inflation of 2022, because energy is such a common input, such increases will have further trickle-down effects on the prices of other goods. (This is intentional and desired, not accidental.)

139. WHAT ARE CARBON CREDITS? WHAT IS CAP-AND-TRADE?

Carbon credits are pollution permits issued by the government that can then be bought and sold. A number of U.S. states (including California) have adopted such a program, often called cap-and-trade. Most economists consider carbon trading to be a second-best alternative to a carbon tax (but better than outright prohibitions), that should be used primarily when/because a tax is not politically feasible. However, economists agree that carbon credits can also contribute to a reduction in CO₂ emissions.

140. WOULD REDUCTIONS IN GHG EMISSIONS SLOW GLOBAL WARMING?

Reductions in worldwide emissions of GHGs are perhaps the only viable way to reduce the speed of global warming in the long run. However, just as the effects of GHG increases on temperature was very slow, the effects of GHG reductions would be very slow. They would barely be noticeable within one generation (30-50 years).

141. ARE THE COSTS OF CLIMATE CHANGE (NOT) GREATER THAN THE COST OF REDUCING EMISSIONS?

The economic costs of emissions reductions need to be weighed against the economic benefits of the same emissions reduction.

It is obviously a fallacy to weigh the cost of an 0.5°C reduction against the benefit from a 3°C reduction. Remarkably, this is a common mistake. Activists often describe the total harm from all global warming (from the 3°C rise) when they discuss the need to reduce emissions. In all reasonable scenarios, the only consideration is to reduce the rise by 0.5°C. The cost of eliminating all 3°C would seem so high that it would be economically near suicidal.

142. WHAT IS THE LAW OF DIMINISHING RETURNS?

It becomes progressively more difficult to get more returns. For example, sweeping the first 90% of the floor may be simple. Sweeping the last 0.1% (e.g., in crevices) could be extremely expensive. Thus, it often makes sense to take care of 90% of a problem in two locations, than 100% in one location. This is, e.g., the case for net-zero goals. It is more cost-efficient to work for a 90% CO₂ reduction in more than one country than for net-zero in just one country.

143. WHAT IS AN ECONOMIC EXTERNALITY?

An economic externality is an effect on a party that was not involved in an economic agreement. For example, when one drives a car, others suffer from exhaust externalities. When one donates to the World Wildlife Fund, others benefit from enjoying the environment. In theory, economics recommends taxing negative externalities and subsidizing positive externalities.

The “Tragedy of the Commons” is an example of a negative externality, in which many private parties compete to use up a “common” resource. The best example may well be the overfishing of the oceans. If one country does not do it, another one will. It’s a race to the bottom.

144. WHY HAS PRIVATE SECTOR INNOVATION NOT SOLVED THE GLOBAL EMISSIONS PROBLEM?

From a social perspective, there is not enough private-sector clean-energy innovation. The incentives are misaligned because the private sector cannot capture all the social benefits of their inventions. (This is an example of a positive externality that should be subsidized by the government.)

145. WHAT IS THE “DOUBLE EXTERNALITY”?

The “double externality” is a term coined by Bill Nordhaus:

• First, there is the research externality. Many of the benefits of innovation do not accrue to the inventor. Therefore, inventors will not invest enough (from a collective social perspective) into research and development. This is the case for all inventions.
• Second, there is the emissions externality. That is, clean technology inventions also reduce the global temperature externality. Both externalities imply that clean-tech R&D remains far below the socially optimal level.

146. WHAT IS THE ECONOMIC APPROACH TO REDUCING BAD EXTERNALITIES, SUCH AS POLLUTION?

Impose taxes on the activities causing these externalities. (Alternatively, “cap-and-trade” is a similar but inferior approach.)

147. WHAT IS AN INTEGRATED ASSESSMENT MODEL (IAM)?

“Integrated assessment models” (IAMs) are the economic models used to analyze climate change. The term “integrated” derives from the fact that these models combine economics with Earth sciences. The models include such aspects as emissions, temperature changes, climate-change harm, economic output, adaptation, investment, government response, etc. Their outputs primarily prescribe how humanity should best raise the price of CO₂ via taxation over time. This is the social cost of carbon. See also Q 135.

IAMs were pioneered by William Nordhaus, with important later contributions by David Stern. All policy analyses — including those by critics of both the status-quo and intervention — are based on them. Despite the models’ large uncertainties and some disagreements, there are no better alternatives. They are the best that scientists and policy-makers have. Paraphrasing Winston Churchill, “they are the worst we have, except for all others.”

148. IS THE OPTIMAL GLOBAL RESPONSE AN IMMEDIATE CURTAILING OF ALL OR MOST GHGS?

The optimal tax policy does not immediately curtail all or even most CO₂ emissions. Too rapid curtailing of CO₂ would likely cause an economic depression the likes of which had never before been seen by mankind. (It would also not be politically sustainable.) Instead, the optimal policy is to start with a reasonable CO₂ tax now (roughly resulting in a 50-100% increase in the cost of gasoline and natural gas). This will give companies and people more time to adapt. The tax should then increase in a predictable fashion over time.

149. WHAT DO IAMS SUGGEST AS A CARBON TAX?

Most IAMs recommend global CO₂ taxes starting between $30 and $80 per tonne of CO₂ emitted. Based on otherwise similar IAMs (though with different parameter inputs), Nordhaus’ recommendations for GHG curtailment have been less aggressive than Stern’s. Roughly speaking, Nordhaus would start his global tax immediately at somewhere around $50/tCO₂, while Stern would start his somewhere around $80/tCO₂.

150. WHY DO IAMS NOT SUGGEST A GHG TAX INSTEAD OF A CARBON-DIOXIDE TAX?

Though IAMs are heavily simplified models of Earth, they are still quite complex. Thus, they consider CO₂ as a stand-in for other GHGs. A good way to think about IAMs is that one should assess the same CO₂ tax on the greenhouse warming potential of other gases (such as a tax of 30 times the CO₂ tax on each tonne of Methane).

151. WHAT WILL BE THE EFFECTS OF CARBON-DIOXIDE CURTAILMENT WITH A GOOD GLOBAL CARBON-DIOXIDE TAX?

In Nordhaus’ model, using a good tax that starts at about $50/tCO₂ and increases over time, by 2070,

More aggressive curtailment policies could greatly lower emissions, CO₂ in the atmosphere, and economic output. However, they would have only a second-order effect on temperature change.

152. WHAT IS THE MOST IMPORTANT INPUT DISAGREEMENT BETWEEN ADVOCATES OF MORE AGGRESSIVE AND LESS AGGRESSIVE GHG CURTAILMENT?

The most important disagreements among scientists about whether emission taxes should be higher or lower are not about economic or technology growth, or even whether the government is benevolent. The main disagreement is about the ethics of polluting the environment today and thereby forcing higher costs on future generations.

153. IS IT ETHICAL TO BESTOW MORE POLLUTION ON OUR DESCENDANTS?

The ethical answer about whether it is appropriate to make our children and grandchildren clean up our messes is not the knee-jerk reaction “of course, not.” Instead, the ethical answer is not at all obvious.

It is true that higher CO₂ emissions today will force higher costs on future generations. However, if history is any guide, there are two other important effects worth considering.

• These future generations will also benefit from the economic growth that these emissions will have caused.
• Second, future generations will also be much wealthier than they are today (and some of this wealth will occur from faster growth brought about by more emissions today). For example, if it were to cost the average person today $5,000 per year on a $60,000 income to curtail CO₂ emissions, should this be done if the resulting pollution imposed extra clean-up costs and harm on the average person in 2100 of $10,000 per year on what will likely then be a $400,000 income?

154. HOW DO THE INTEGRATED ASSESSMENT MODELS HANDLE INCOME INEQUALITY?

By and large, IAMs ignore income inequality. It is also unclear how economic models should consider inequality, even conceptually. The problem is easy to understand but difficult to answer.

For example, let’s say that there are three countries, with incomes of

Try to answer two philosophical questions:

1. If inequality is in itself undesirable, would it be endorsable to lower the wealth of the rich country even if it has no effect on other countries?
2. If curtailment actions were to raise the incomes of the poor country by 50% and lower the incomes of the rich country by 10%, the world would drop from a total income of $111,000 down to one of $101,500. Would this make the world better off? (A hypothetical transfer of, say, $1,000 from the rich to the poor countries could reduce inequality more than the curtailment action would — but such transfers rarely take place in the real world.)

155. HOW MUCH TRUST DO YOU PLACE IN THE IPCC?

The Earth science researchers at the IPCC are the best in the area, although they do have a bias akin to a lung cancer specialist worrying about lung cancer all the time. They also have (informed) biases, akin to those that economists have about free markets.

I am less enthused about the IPCC social science division which issues the “Shared Socioeconomic Pathways (SSPs).”

I have little trust in the non-scientific leadership at the IPCC. It is turning ever more political by the year. In advocating for the leadership posts, the candidates’ platforms were not on improving the science but on advocacy about fighting climate change. I fear this is counterproductive in keeping the IPCC a credible neutral scientific source.

156. HOW MUCH TRUST DO YOU PLACE IN THE “SHARED SOCIOECONOMIC PATHWAYS” (SCPS) PUBLISHED BY THE IPCC?

Not a lot. Note that I am a social scientist by trade. Fortunately, IPCC report readers can still rely on their main expertise, their RCPs (representative concentration pathways). (This question refers only to the shared socioeconomic pathways, not the Earth pathways.)

157. DO PEOPLE STILL DOUBT CLIMATE CHANGE?

Surveys suggest that most people now recognize climate change as a real and serious threat.

158. HOW MUCH ARE PEOPLE WILLING TO SPEND ON FIGHTING CLIMATE CHANGE?

Survey suggest that most people are willing to spend a few tens of dollars per year. It would cost a few thousand dollars per year in order to curb global temperature by 0.5°C.

159. HOW MUCH ARE YOUNGER WELL-OFF PEOPLE WILLING TO SPEND ON FIGHTING CLIMATE CHANGE?

Even the average German 14-29 years old — perhaps the most concerned activist demographic in the world — would not be willing to forego driving a car and flying off to vacation in other countries. The talk is cheap; the walk is hard.

160. WILL PEOPLE BECOME MORE WILLING TO SPEND MORE ON CLIMATE MITIGATION AS CLIMATE CHANGE GETS WORSE?

It is my view that these attitudes will not change even as the world warms. There will be a lot of clamoring, but very little sacrificing when it comes to opening one’s wallet — especially in the countries that will matter most (China, India, South-East Asia). Remember also that any emission reductions at that point would still take decades to make any notable impact on the problem.

Arguably, they will do the opposite — spend less on mitigation as they spend more on adaptation. The future will tell.

161. GRETA THUNBERG: “HOW DARE YOU?”

Greta Thunberg’s indictment of the world’s lack of action on climate change is a common perspective especially among wealthy, privileged teenagers living in some of the richest countries in the world.1 But consider:

• The fact that her life expectancy is now far above 30 years of age and that she will not likely have to spend a short life of hard physical labor is indisputably greatly due to the same forces that have caused global emissions to rise.
• Climate change depends only on global emissions, not on OECD emissions. Even drastic reductions in OECD emissions will not make a large difference. In order to slow down global warming, the reductions have to be worldwide.

Greta’s advocacy for stopping emissions from fossil fuels is not a common perspective of billions of poor families in poor countries struggling to survive. Economic growth has always been the only way out of poverty, and economic growth requires energy. I believe she is not fully aware of the trade-offs involved.

By focusing on activism in wealthy countries and the opinions of well-off, outspoken intellectuals, the media have greatly exaggerated the readiness of the world to fight climate change.

162. WILL FOSSIL FUELS PREMATURELY KILL MILLIONS OF PEOPLE?

Yes, but mostly through their localized particle emissions rather than through their contribution to climate change.

163. WILL CLIMATE CHANGE PREMATURELY KILL MILLIONS OF PEOPLE?

The World Health Organization estimates that there will be an additional 250,000 deaths per year due to climate change over the next 30 years. Some academics now predict as many as 1,000,000 early deaths per year by the end of the century, mostly in Africa (where population has been growing from 350 million in 1850 to 3.5 billion by around 2050). However, the uncertainties here are very large.

See also the next question.

164. IN ORDER TO REDUCE MILLIONS OF CLIMATE-CHANGE DEATHS, SHOULD STRONGER EMISSIONS CONTROLS BE INSTITUTED?

Although there is no one that could do so (rendering this question ultimately futile), this common narrative seems incorrect:

• Most of the additional deaths forecast by the WHO cannot be reduced by curbing CO₂ emissions. First, the effect of curbing emissions on reducing atmospheric CO₂ and eventually temperature will be small (perhaps 0.3-0.5°C). Second, the temperature effects of emission curbs will not take hold for at least one generation (30 years).
• Most of the additional deaths that are forecast will be due to malnutrition and malaria, not to direct heat-stroke or heat. That is, these deaths could be easily prevented and treated in many other ways. These deaths say more about the world’s health systems and poverties than they say about climate change.
• Although temperature increases will likely kill millions, the money necessary to fight climate change will most likely be diverted from economic growth and will possibly kill hundreds of millions of people. Economics is about trade-offs — here the worst and most painful trade-offs imaginable.

Of course, it is cold comfort for the millions of people that will die prematurely from climate change that hundreds of millions of others will no longer die from privation prematurely. (Just imagine that those dying earlier are your own family!)

165. HOW WILL CLIMATE CHANGE COMPARE TO TODAY’S MALARIA IN TERMS OF HUMAN SUFFERING?

By any measure, Malaria is killing an order of magnitude more people (especially children) today than climate change is currently forecast to kill.

We can only hope that scientists will eradicate the responsible Anopheles mosquito as soon as possible. (This is already technically possible today. For anyone against it, please relocate together with your children to one of the regions where Malaria is endemic. Then you will have the moral authority to speak against it.)

Note that I am not saying that climate-change deaths are imaginary, less important, or neglectable. The world as a whole would be better off slowing climate change.

166. SHOULD ENERGY COMPANIES AND OIL BARONS BE HELD RESPONSIBLE FOR THEIR PAST HARMFUL EMISSIONS?

This is a dangerous argument. The pollution from energy provision has not only cost millions of lives (mostly in particle pollution), but it has also raised billions of lives and thereby saved millions of them. So if energy companies deserve to pay damages for the harm they have caused, do they also deserve compensation for the good they have caused?

This question is also irrelevant. It has no reasonable probability of happening. At most, some countries will be able to tax their own fossil-fuel companies, but the important countries will not tax them and send the tax revenues to other countries.

167. SHOULD RICH COUNTRIES BE HELD RESPONSIBLE?

Although there is no one that could do so (rendering this question ultimately futile), this common narrative seems incorrect.

This is another dangerous argument. The development of rich countries has also indirectly helped many poor countries. For example, before modern fertilizers, many millions died of hunger. Before modern medicines, many millions died of illnesses.

And how do we credit or blame rich countries for making it possible that many more people have been born in poor countries than in rich ones? Africa will have 4 billion people by 2100. In 1960, Africa used to have 0.2 billion people. Should rich countries then be responsible for the poverty of 0.2 billion people or for the poverty of 4 billion people?

This question is also irrelevant. It has no reasonable probability of happening.

168. COULDN’T RICH PEOPLE, RICH COUNTRIES, AND RICH ENERGY COMPANIES PAY FOR THE CLEAN-UP?

These parties are simply no longer big and rich enough to carry this large an expense on behalf of 8 billion people. Instead, the cost would have to fall on most of the world’s population collectively — rich countries and poor countries; rich people and poor people. (And, of course, assessing taxes on all rich people of the world is not how the world works, anyway.)

169. AS CLIMATE ACTIVISTS OR FOSSIL-FUEL PROPONENTS, SHOULD WE VOTE X?

We should try to avoid poisonous politics as much as we can. It is a big problem that the subject has become so heavily politicized and part of the culture wars. Tribalism does not make for good policies.

The debate should not be about “more” vs. “less” of old stupid policies, but rather it should be about better “smart” vs. worse “stupid” policies. In an ideal world, we could use the hearts of liberals and the minds of libertarians to do better. Indeed, we may not even need to throw more money at more policies to reduce worldwide and local emissions. Instead, we need smarter policies to effectively reduce worldwide and local emissions.

170. WHY IS HUMANITY NOT DOING THE SENSIBLE THING AND FIGHTING CLIMATE CHANGE MORE VIGOROUSLY

Humanity is not doing the sensible thing fighting climate change for the same reason that it is not eliminating weapons, militaries, and wars. It is not in the self-interest of relevant actors to do so, even if everyone would be better off if all could jointly commit to disarming.

171. HOW SHOULD HUMANITY RESPOND TO THE PLANETWIDE CLIMATE EMERGENCY?

The question of how “humanity” should respond is really a non-sequitur, even though it often animates the public debate. There is no “humanity” capable of responding. Humanity is not a (Star Trek) Borg-collective (for non-Trekkies, the reference is to collective thinking or single-minded response). There are only individual decision-makers capable of responding. The world outcome is not the engineered collective solution to a worldwide problem, but the result of the actions of many individual decision-makers. Scientists should only analyze (and try to nudge) real individual decision-makers.

This is the strongest opinion that I hold. It implies that much of the public debate is futile.

172. WHAT ARE THE WORST MISTAKES IN THE PUBLIC DEBATE ABOUT CLIMATE CHANGE?

It can be argued about what the worst mistakes in climate change debates are. Here are my own opinions:

• It is the treatment of humanity as if it was the (Star Trek) Borg collective. The collective analysis of what the global carbon tax should be from a global human collective perspective seems mostly irrelevant. The only relevant analysis seems to me to be what actual individual decision-makers will do and how these decision-makers can be influenced to alter their decisions.
• It is the focus on ineffective potential (and often expensive) non-solutions:

The list of ineffective and inefficient non-solutions includes but is not limited to:

• Carbon footprints are not going to work — they are not even pinpricks. They are a “wellness” approach, not a realistic approach to changing the CO₂ concentration in the atmosphere.
• Tightening belts is not going to work — people won’t do it.
• Local and regional approaches are not going to work — they are too small.
• United Nations treaties are not going to work. The important countries are (understandably) too self-interested.

In my opinion, the only efficient and effective solution is for the world to invent and commercialize better and cheaper energy (storage) solutions faster. They would then be adopted voluntarily both in OECD and non-OECD countries on wide scales. Innovation can also be helped when countries adopt reasonable fossil-fuel taxation.

It is my fear that focusing on unrealistic solutions will distract from the attention required for realistic solutions. This will be elaborated below.

173. HOW MUCH WOULD ELIMINATING GHG EMISSIONS COST (AT THE MOMENT)?

An approximate estimate for the aggregate worldwide cost of fighting climate change is that it would be on the same order of magnitude as the worldwide spending on higher education.1 If rich OECD countries were to also take on the cost of eliminating GHG emissions on behalf of poor non-OECD countries (which I consider to be highly unlikely), a good estimate would be that it would be roughly the worldwide spending on all education. (This is not to suggest that countries should redirect their expenditures from education to fighting climate change. It is only presented to give some perspective on the costs involved.)

174. WILL INCREASING TEMPERATURES CONVINCE WORLD GOVERNMENTS TO VOLUNTARILY CURTAIL EMISSIONS?

It is unlikely that increasing temperatures will convince world governments to curtail emissions:

1. The costs of wide curtailment are very high.
2. It takes about one generation before the impact of curtailed emissions even shows up in slower temperature growth.
3. Even drastic curtailment will not stop climate change, only slow it down — often barely noticeable in most parts of the globe.
4. No country would reap more than about 10% of the benefits of any curtailment measures it would undertake — and some countries would likely even benefit from global warming, such as Russia and Canada.
5. Public attention spans are unlikely to keep fixating on global warming when there is economic hardship (and opposition politicians can offer to spend the curtailment cost elsewhere). This will be especially the case in economic recessions.

175. CAN AND WILL OECD COUNTRIES TAKE CARE OF THE GLOBAL GHG EMISSIONS PROBLEM?

Absent new cheaper clean technology, the OECD can and will almost surely not be able to take care of the global problem. The OECD is only a minority player. Its cost of taking care of the world emission problem would roughly be comparable to the OECD’s total spending on public education. OECD country populations will not be willing to engage in this sort of sacrifice on behalf of the greater good, especially while China, India, and other countries will continue to grow their economies and emissions.

176. CAN AND WILL NON-OECD COUNTRIES TAKE CARE OF THE GLOBAL GHG EMISSIONS PROBLEM?

Absent new cheaper clean technology, non-OECD countries can and will almost surely not be able to take care of the global problem. They are too poor to worry about other countries in the distant future. Most non-OECD countries (and especially the most important ones) are more concerned about how they can grow their economies in order to reduce widespread poverty.

177. WHAT ARE THE BASIC REQUIREMENTS TO CHANGE THE WORLD’S CARBON-DIOXIDE EMISSION TRAJECTORY?

The two basic requirements of any solution to changing the world’s CO₂ emissions trajectory are:

1. The change must be big and it must scale to non-OECD countries.
2. The decision-makers must voluntarily want to adopt them. This usually means that GHG reductions must be in their self-interests.

178. WOULD THE WORLD BE BETTER OFF WITH A CARBON-DIOXIDE TAX?

Yes, the world would be better off with a CO₂ tax.

179. IS CLEAN TECHNOLOGY A SUBSTITUTE FOR AN EMISSION TAX?

Clean technology is not a substitute for an emission tax. Ideally, clean technology would be a complement to an emissions tax and vice-versa. An emissions tax would incentivize industries to come up with cleaner technologies.

As for me, I am in favor of a (reasonable) CO₂ tax. I just do not believe that it will be in the self-interest of enough countries to enact and enforce meaningful CO₂ taxes, at least much beyond what local harmful pollution effects can justify.

180. WHY DO COUNTRIES NOT REDUCE MILITARY SPENDING TO REDUCE EMISSIONS?

Countries are not reducing military spending for the same reason that they are not curbing their CO₂. It may be globally optimal, but it is not in their self-interests.

181. IS A GLOBAL CARBON TAX BASED ON THE SCC A USEFUL APPROACH?

My view is that discussing and pursuing a global CO₂ tax is not a useful approach. There is no world dictator or institution that could enact and enforce such a tax. An SCC tax is therefore a theoretical conceptual guiding number and not a practically implementable one.

182. WILL NATIONS AGREE TO AND ENFORCE A GLOBAL CARBON TAX IN NEGOTIATED ARRANGEMENTS?

It is subject to debate whether countries will agree to and enforce a global carbon tax. My view is highly pessimistic. This view is informed by the following:

1. The magnitude of the required sacrifice is too high to maintain public support over generations in all but a few countries.
2. The benefits from not signing on to any such treaty are large for non-signers. This makes it very different from, say, a defense alliance like NATO; or even the Montreal Ozone protocol, signing onto which was widely considered to be even in the self-interest of signing nations.

Other scientists are more optimistic than I.

183. DOES THE MONTREAL OZONE PROTOCOL SHOW THAT A GHG TREATY IS POSSIBLE?

The Montreal Protocol is not a good analog showing that pollution treaties are viable. At the time, the EPA assessed the U.S. benefits of unilaterally curtailing ozone at $1,400; the U.S. cost at about $20. It further assessed the cost of the Montreal Protocol to be the same $20, but the benefit to rise to $3,500. In contrast, the proposed net costs of a GHG treaty range from $5,000 to $20,000 per year, not –$3,500.

184. WHAT TARGET ARE UNITED NATIONS CONFERENCES WORKING TOWARDS?

At this point, it is unclear what the United Nations target is. The Paris Agreement of 2015, adopted by 196 parties, was to limit climate change to well below 2°C, ideally 1.5°C. However, the reductions were neither mandatory nor enforceable. All countries have been falling behind their declared goals. The energy crisis of 2022 has further demonstrated the priorities of the signers. Even Germany has restarted its coal plants.

185. WHICH COUNTRIES HAVE PLANS COMPATIBLE WITH THE 1.5°C PARIS AGREEMENT OF 2015?

According to the Climate Action Tracker, not one of 181 participating countries has made good progress towards meeting the 1.5°C Paris Agreement goal. As of August 2022, the closest countries are Costa Rica, Ethiopia, Kenya, Morocco, Nepal, Nigeria, Norway, the Gambia, and the United Kingdom. And arguably, most progress was due primarily to the availability of cheaper clean-emissions generation technology.

186. WILL UNITED NATIONS TREATIES WORK?

My view is that United Nations Treaties will not work to effectively curb climate change. Virtually no large country so far has made good on its past promises. Russia, China, and India have already “left the building” (in the last COP meetings in Glasgow), as did the U.S. under the Trump Administration. Given the geopolitical competition between democratic and non-democratic countries (the OECD vs. China, Russia, and Iran), it is difficult to see how these blocs could cooperate on an issue as big and expensive as climate change.

187. CAN DEMOCRATS RUN ON A PLATFORM OF FIGHTING CLIMATE CHANGE?

No one can stop politicians from running on platforms that are popular with their base. However, it makes as much sense to stand on a platform of fighting climate change, as it is to stand on a platform fighting for world peace. It is beyond the United States to reduce the carbon emissions of the world by reducing its own carbon emissions. The only way to do so is to incentivice research and development (and usually this is not by local deployment of cleaner technology).

Unfortunately, real-world governments are notoriously dysfunctional in addressing even the clearest of problems. Paraphrasing Herman Wouk, real-world governments are master plans designed by geniuses that unfortunately have to be executed by idiots.

188. CAN CORPORATE INITIATIVES REDUCE EMISSIONS?

It is highly unlikely that corporate initiatives will meaningfully reduce worldwide emissions. Companies are set up to earn profits, not for social purposes. Companies will engage in reducing emissions (or at least appear to reduce emissions) when it improves their bottom lines. Lip service and public relations have become big business, especially for many consulting firms. Moreover, even if many companies succeeded in reducing their own emissions, they are simply not big enough to meaningfully change the world’s emissions.

189. WHAT DOES E.S.G. STAND FOR?

E.S.G. stands for “Environmental, Social, Governance.” One component of the environmental rankings is climate-change related. See also the next question.

190. IS E.S.G. EFFECTIVE IN SLOWING CLIMATE CHANGE?

All evidence suggests that it has no chance. Its proponents often tout phyrric victories, and even those are best described as greenwashing.

They are very effective only in requiring armies of consultants and justifying new bureaucracies and (useless) regulations. Environmental laws and regulation are far better approaches to environmental problems than attempts to get companies to count up emissions.

191. IS INVESTING IN E.S.G. FUNDS HELP FIGHTING CLIMATE CHANGE?

All evidence suggests that it has no chance. Its proponents often tout phyrric victories, and even those are best described as greenwashing.

If you want to do good for the environment, there are better organizations to donate to. If you want to reduce global climate change, only investment in and implementation of green technologies have a good chance of helping.

192. HOW USEFUL ARE E.S.G. RATINGS IN FIGHTING GLOBAL CLIMATE CHANGE?

Environmental ratings are not about how much companies reduce their contribution to climate change, but about how exposed companies are to damages caused by climate change. Thus, E.S.G. ratings are not good guidance for fighting climate change — and possibly the opposite.

E.S.G. ratings are also “in the eye of the beholder,” with different agencies offering very different assessments.

193. HOW USEFUL IS DIVESTMENT FROM FOSSIL FUEL COMPANIES?

All evidence suggests that divestment and boycott efforts from fossil fuels have been unsuccessful in reducing emissions. Divestment efforts seem more like a “wellness approach” to climate change and more public relations than substance. Moreover, even if divestment were successful, it is unclear what it would accomplish beyond making a public statement. Fossil-fuel companies will not reduce their fossil-fuel activities because their shares will simply be purchased and held by other investors. This will not slow down their exploration and emissions, much less global warming. Divestment efforts are distracting from more productive approaches — such as investing more into inventing better energy storage technologies.

194. WHAT ARE THE MOST VIABLE CARBON FOOTPRINT REDUCTIONS?

For the majority of rich-country middle-class individuals, the easiest large target to reduce one’s global footprint is to give up flying. The next targets would be reduced heating and cooling, better insulation, and shorter commutes.

195. HOW EFFECTIVE ARE CARBON OFFSETS (E.G., FOR FLIGHTS)?

Carbon offsets are good public relations but ineffective for meaningfully changing global emissions, the atmospheric CO₂ concentration, and global temperature change.

196. IS BICYCLING A WAY TO REDUCE ONE’S CARBON FOOTPRINT?

This is not clear. The human body is an engine — and not a very efficient one. It needs to be fed. Growing human food requires a lot of energy. To the extent that bicycling prolongs life, longer-lived people need to be fed more.

197. CAN PERSONAL CARBON FOOTPRINTS MAKE A DIFFERENCE IN THE WORLDWIDE CO₂ ?

Personal carbon footprints cannot make a difference. They are the ultimate “wellness approach” to climate change. The real problem is not how to convince a minority of the “salon faithful” in rich countries to eat vegetarian. It would rather be to convince 8-11 billion people in poorer countries to voluntarily slow down improving their living standards in order to slow down global warming (a change that will benefit mostly other countries many decades later).

Moreover, even for the salon faithful, the effectiveness of carbon-footprint campaigns has been more like “New Year’s Resolutions” than consistent life-long changes. Few have given up flying. You may wish global footprint-watching had a large effect, but the evidence suggests it has not.

There is also no knowledge deficit: High-emission activities have been widely understood for decades and footprint concerns have not reduced them. There is no reason to imagine that carbon footprint campaigns will soon begin to work on a much larger scale.

Some climate activists now consider personal-footprint initiatives to have been a ruse by fossil-fuel companies, invented for the purpose of distracting and pushing the responsibility away from themselves and onto individuals. Carbon footprints were indeed first proposed and promoted by British Petroleum (BP).

198. SHOULDN’T I REDUCE MY CARBON FOOTPRINT? WHAT IF EVERYONE REDUCES THEIR CARBON FOOTPRINTS?

It is a fallacy to connect your decision to everyone else, especially in this case. Whatever you do will not change the decisions of billions of others. They will do whatever they will do, regardless of what you are doing.

199. DOES “SETTING AN EXAMPLE” HELP?

“Setting an example” is unlikely to sway poorer populations (such as those in India or China) that it should now be their moral obligation to follow. (And these countries can always point to past emissions by these newly-converted evangelists as evidence of their hypocrisy.)

200. WILL SHAMING BE USEFUL?

Shaming is unlikely to help. For example, India has declared the war on poverty its top priority. To do so, it will have to emit many extra gigatonnes of CO₂ over the next decades. It seems unlikely that calling out the Indian, Chinese, or other East-Asian governments will make much difference. Views can differ on whether it is helpful on the margin or whether it does more to offend the public in these countries and to create a strong backlash.

201. HOW USEFUL ARE CITY-WIDE OR STATE-WIDE CHANGES IN CARBON EMISSIONS? HOW USEFUL ARE “ZERO EMISSIONS” PROGRAMS?

City-based or state-based reductions in CO₂ emissions are good public relations but ineffective for meaningfully changing global emissions, atmospheric CO₂ concentrations, and global warming — except when they help pioneer technologies and thereby make them substantially cheaper for other locations around the world.

202. CAN ONE BE AN ENVIRONMENTALIST AND BE AGAINST SOME SPENDING ON REDUCING GHG EMISSIONS?

Yes, one can be an environmentalist and still be against spending on reducing CO₂ emissions, when the “bang for the buck” is too low. One can advocate reallocating some climate-change-fighting expenditures to other worthwhile philanthropic activities instead (such as attempts to protect the ocean or protect other biospheres).

203. IS FIGHTING CLIMATE CHANGE ABOUT SOCIAL JUSTICE?

Climate change is not about social justice. This is simply a different goal. On rare occasions, there can be overlaps. On more common occasions, political coalitions come together on both goals and later split the pie into pieces based on influence outside the political process.

204. IS CLIMATE CHANGE ABOUT HELPING PROTECT THE POOR OR POOR COUNTRIES?

Climate change is not about helping the poor in poor countries. The general apathy of richer people and richer countries with respect to the miseries of even the poorest of the poor today suggests that the claimed interest in their welfare in 50-100 years is not a primary concern. The proclaimed concerns seem to be more about rhetoric than reality.

205. WHAT APPROACHES CAN CHANGE THE WORLD’S GHG EMISSION TRAJECTORY?

As already noted in Q 177, approaches must satisfy two criteria:

1. The change must be big and scale to non-OECD countries;
2. The decision-makers must want to adopt them. These criteria usually imply that changes must be in their self-interests.

Therefore, the two approaches that could realistically change the world’s CO₂ emission trajectory and therefore eventually the CO₂ concentration in the atmosphere and global warming are

1. Improved Clean Technology.
2. Local fossil fuel taxes that can be justified on the basis of their reductions in local pollution.

There are many other changes that would be helpful, effective, and efficient in reducing emissions, but that would not be decisive.

206. DOES CLIMATE ADAPTATION HELP?

Climate adaptation helps those affected by climate change. Adaptation is usually greatly in their self-interest and often quite affordable. Adaptation works much faster than reducing CO₂ (which will take many decades to show any effect even if it can be accomplished). On the flip side, successful adaptation does reduce the incentives of decision-makers to reduce emissions today. (Economists call this lack of incentive “moral hazard.”)

207. ARE NON-GLOBAL FOSSIL FUEL TAXES VIABLE?

One can disagree about how politically and economically viable local fossil fuel taxes will be.

I believe fossil-fuel taxes can be viable even if countries and their politicians remain entirely self-interested. Fossil fuels have terrible and visible health effects, mostly from their particle pollution. They kill millions of people every year. Some estimates are that fossil fuel taxes as high as $100/tCO₂ can be justified by local pollution. This calculation is area- and population-dependent. (In the United States, the justifiable local tax would be between $15/tCO₂ and $40/tCO₂.) The local tax is lower than the globally justifiable tax on CO₂, but it is not small. Thus, I believe that it should be possible to convince populations with smart marketing campaigns that it is in their own interests not to see their parents and children poisoned. Some OECD countries may also adopt fossil fuel taxes for political and altruistic reasons. On the flip side, fossil fuel companies have powerful political influence. This is most obvious in the fact that fossil-fuel net taxation in the world today is negative.

208. WHAT IS THE MOST SERIOUS PROBLEM OF AGGRESSIVE GHG TAXATION?

Companies and industries that produce exportable good can escape to other locales that are less highly taxed. When it becomes cheaper to produce such goods abroad, what stops the next generation of plants from migrating there? (It’s what sound business logic may suggest.) This argument does not apply to non-exportable goods (like real-estate).

This is not a theoretical ivory-tower concern. This dynamic has eroded the industrial heartland of the United States over the last 30 years. Much production has moved to China and other countries, where labor, energy, and production have been cheaper. (After a while, the local expertise may get lost, too.) The end result is often not only local harm but also higher worldwide emissions. Keeping the local business environment attractive enough must be the first order of business. As Jean-Baptiste Colbert so aptly noted, “The art of taxation consists of plucking the goose so as to obtain the most feathers with the least hissing.”

209. ARE U.S. ECONOMISTS FOR OR AGAINST FOSSIL-FUEL TAXES?

Most U.S. economists are in favor of appropriate fossil-fuel taxes. I agree with a public 2019 statement (signed by all Nobel Prize winners) that endorses fossil fuel taxes even unilaterally in the United States. The statement acknowledges the concern that care must be taken so that fossil fuel taxes and regulations will not drive U.S. industries abroad.

210. DOES “SETTING AN EXAMPLE” USING TECHNOLOGY HELP?

See also Q 199. The only “setting an example” that can make a difference are those in which early adoption helps drive down the commercial cost of clean technology. The most prominent case of this effect was the large German subsidy program that helped commercialize wind power. When the program began, the cost of wind power was over $300/MWh — a cost that was born mostly by German electricity customers. Today, after having built up economies of scale, the cost has come down to about $40/MWh.

211. IS REFORESTATION HELPFUL?

Reforestation is likely helpful. However, there is an important complication. It is true that forests reduce greenhouse gases by converting air CO₂ into a useful product (timber) and reap local environmental benefits at low cost. But tree canopies are also relatively dark. Their low albedo makes them absorb more sunlight, which can raise global warming. More research is needed.

212. CAN OTHER PLANTS BE FARMED TO REDUCE CARBON-DIOXIDE?

There are many other plants (like some forms of algae, bamboo, or hemp) that can also be farmed to extract CO₂ out of the air.

213. WHAT ARE THE ADVANTAGES AND DISADVANTAGES OF FOSSIL FUELS?

The advantages of fossil fuels are: (1) Existing infrastructure to extract and distribute them. (2) Low extraction cost. (3) Low transport cost for oil and gas, though not for coal. (4) High energy density (a lot of energy in a small volume and mass). (5) Good disaster safety record. (6) Near-perfect heat efficiency.

The disadvantages are: (1) Highly polluting. (2) Highly efficient only for heat generation.

214. WHAT ARE THE BIGGEST COST DIFFERENCES AMONG ELECTRICITY PLANTS?

The biggest differences are not their fuel source, but whether the plant has already been built or not. Once built, most types of plants can produce electricity at low cost.

215. WHAT IS BIOMASS? IS IT RENEWABLE? IS IT CLEAN?

Biomass energy (renewable energy derived from burning biological matter, such as wood, crop residues, or garbage) is among the dirtiest ways known to humankind to generate heat or electricity. Ideally, biomass energy would only be used when the alternative is to allow the matter to decay into methane and/or no other sources of energy are available. (One cannot blame people for burning wood in a stove when they don’t have electricity or fossil fuels.) Unfortunately, some government schemes consider biomass a “green” renewable form of energy and thus have subsidized it.

216. IS COAL STILL ECONOMICALLY VIABLE?

On a cost basis, coal is no longer cheap enough in most locations around the world. This is because it is expensive to mine and transport coal and because it has terrible local health effects. Even a small carbon tax would likely render it even less competitive in most (though not all) locations. This is not only the case for building new plants, but even for already existing plants.

Remarkably, the building of any new coal plants (as in China) represents a triumph of politics over capitalism. The Chinese coal sector has large employment.

However, the energy crisis of 2022 has led many countries, even Germany, to reopen already shuttered coal plants. Some may even contemplate building new ones now.

217. WHERE ARE TODAY’S COAL PLANTS? HOW MUCH POWER CAN THEY GENERATE

About 0.25 GW are under construction or on the drawing board, three-quarters of which are in China and India. Almost no coal plants are under construction or on the drawing board in OECD countries.

218. WHAT COUNTRIES ARE STILL PROMOTING COAL?

There are large coal-plant building programs in China and more moderate ones in the rest of Asia. Once built, these plants will make it profitable to burn coal for many more decades. There are practically no new coal plants planned in the OECD, although old ones are still operating and some have been reopened in 2022.

219. IS NATURAL GAS STILL ECONOMICALLY VIABLE?

In many locations, natural gas is the cheapest source of energy. Thus, it is economically the most viable source of energy. Indeed, for this reason, it is best described as the 500-pound gorilla in the room. It is the alternative that clean energy will need to beat in terms of price in many countries, especially in the United States.

220. IS OIL STILL ECONOMICALLY VIABLE?

Oil, diesel, and gasoline remain the cheapest source of energy for transportation — barely. This situation is in the process of changing for cars and soon trucks that have access to the electric grid. Oil is likely to remain the most viable economic source for fueling ships and airplanes for many decades.

221. DOES ETHANOL MAKE SENSE?

Ethanol makes neither economic nor environmental sense. It probably costs more than one gallon of diesel fuel to raise one gallon of ethanol. Ethanol is also harmful to engines. It exists only because politicians compete to win the early primaries in Iowa, so they have been delivering massive subsidies to this industry.

222. IS HYDROGEN ECONOMICALLY VIABLE?

Green hydrogen is not economically viable. Even if electricity were free (the highest production cost component), green hydrogen would still cost more than natural gas. It is implemented today primarily because of large government subsidies. It is an example of how public enthusiasm coupled with ignorance can drive bad policy.

Green hydrogen is also not likely to become viable for energy storage. It is many times more expensive than stored energy in other forms (not only NatGas, but also batteries and heat reservoirs). Hydrogen will also not play a role in industrial heat generation, because it is cheaper to transport electricity directly to a heat storage reservoir and then tap this reservoir.

Green hydrogen may eventually (in the very long run) play a role in transportation applications that cannot be connected to the electric grid (such as airplanes and ships).

223. IS NUCLEAR POWER STILL ECONOMICALLY VIABLE?

Current nuclear technology is not economically viable. Overregulation has not helped, but nuclear energy has also not succeeded in countries with weaker regulation. The biggest problem of today’s nuclear technology is the fact that traditional reactors cannot compete with cheaper natural gas (and perhaps soon with clean wind and solar energy) in most locations.

224. IS NUCLEAR POWER SAFE?

Nuclear power plants may be among the safest plants on the planet, but their potential for disaster is also enormous. Moreover, they are absolutely not perfectly safe. Many unforeseen incidents have shown that they are not as safe as they were touted to be. Current designs can and have melted down. Simply put, existing reactor technology has not been safe enough.

225. WHAT ARE OTHER PROBLEMS OF NUCLEAR ENERGY?

• The nuclear waste problem could be solved. It has been created by stupid government promises to take back nuclear fuel, and then paying firms to store them rather than to reuse the fuel.
• The proliferation problem (of radioactive toxic waste material, not of a nuclear bomb) is more difficult.

226. COULD NUCLEAR POWER BECOME MORE COMPETITIVE?

There are promising new nuclear reactor designs on the drawing board that could improve both safety and economics. The most promising designs are small and mass-producible and based on passive safety technology. More research — and development and deployment — is necessary to understand how competitive new designs for nuclear plants could become.

227. ARE BATTERIES ECONOMICALLY VIABLE?

Batteries are already economically viable for all mobile transport applications (such as cars) and for modest grid-storage requirements (up to about four-hour storage).

Even the best batteries remain too expensive for full-night grid storage. This is because lithium batteries scale poorly (doubling capacity typically requires doubling battery expense) and wear too quickly (lasting only about 1,000 charging cycles). Flow batteries have the potential to overcome both problems for longer-term grid storage. However, they are not yet ready.

Batteries will not likely become economically competitive for storing energy that will eventually be used to create heat or cold. It will likely always be cheaper to use electricity to generate and store the heat or cold in an insulated reservoir than to store the electric energy in a battery.

228. WHAT IS THE MOST IMPORTANT CLEAN-ENERGY DRAWBACK?

The most important clean-energy drawback is that solar and wind power can be generated only when nature cooperates. Thus, they require storage for “use on demand.” Although clean electricity generation plants are already as cheap as the best fossil fuels are (in natural gas combined-cycle turbines), the high cost of electricity storage renders clean technology still too expensive for 24/7 coverage.

If the cost of energy storage were to come down by one order of magnitude, fossil fuels would lose most of their use cases.

229. COULD CLEAN ENERGY RESEARCH AND DEVELOPMENT FAIL?

Any individual new clean energy technology is more likely to fail than not. However, it seems highly unlikely that clean energy will not make rapid progress with so many different alternatives in research and development. (More government support could improve the chances of success.)

230. IS THERE ENOUGH UNUSED LAND AREA TO SUPPLY THE WORLD WITH SOLAR ENERGY?

There is more than enough unused land area to supply the world with solar energy a few times over. Although the required area is large, so is the problem. Moreover, wherever solar is not abundant, usually wind is. And the necessary land is often cheap. Even agriculturally unproductive land is suitable for solar PV and wind farms. The following yellow box on the map shows a perspective for the area needed to cover an amount equal to all of today’s US electricity generation (though it would make no sense to place all solar panels in Nevada).

231. IS THERE ENOUGH LITHIUM (AND COBALT AND …) TO SUPPLY THE WORLD WITH BATTERY STORAGE?

Yes, there is more than enough lithium and other chemicals available to supply the world with battery storage. In fact, there are no serious medium-term and long-term hindrances to mining the materials needed for clean energy technologies. There will, however, be short-term hindrances. Regulatory processes typically require a full decade even when it comes to the most environmentally-benign new mines.

There are also many viable alternative battery chemistries if the currently most cost-effective chemistries were to lose their cost advantages because of increases in their raw material prices. In fact, some alternative chemistries may replace lithium batteries for grid storage regardless of mining prices.

232. DOES CLEAN-TECH HAVE ENVIRONMENTAL AND RECYCLING PROBLEMS?

Even clean technologies do create some environmental harm and have some recycling problems. But their problems are very small compared to those of far more toxic fossil-fuel technologies, and they can be further reduced with better planning.

233. IF ONE COUNTS IN PRODUCTION EMISSIONS, ARE ELECTRIC CARS STILL ENVIRONMENTALLY FRIENDLY?

Electric vehicles are environmentally much friendlier than combustion vehicles.

There have been allegations that the environmental impacts of clean-tech sourcing undo their environmental advantages. This is not true and probably propaganda spread by proponents of fossil fuels, usually peppered with half-truths and half-lies.

The most valid concerns arise when electric vehicles are fueled by electricity from coal-fired plants (as they are, e.g., in China and India).

234. IS CLEAN-ENERGY TECHNOLOGY (INAPPROPRIATELY) SUBSIDIZED?

Clean-energy technologies are now indeed often subsidized. However, so is the main competitor (fossil-fuel technology) in most parts of the world. The latter subsidies have been going on significantly longer and at much higher levels. Ideally, fossil fuels should have been taxed at their environmental externalities (local and global), rather than subsidized. Unfortunately, this is not the world we live in.

235. WILL THERE BE BUMPS ALONG THE WAY TO A CLEAN-ENERGY ECONOMY?

There will be many little and bigger bumps along the way, especially in the short run. Political considerations will continue to influence popular choices and make the transition to clean energy more expensive than it should be. NIMBYism is slowing down the needed expansion of electric grids in many countries.

Dumb political choices — such as misguided environmentalist policies that are too expensive for their effects — can also cause backlash for policies that will have to be maintained over generations in order to have an impact. Fossil fuel companies are working hard to lobby politicians and regulators in order to slow down the changes.

236. AM I IN FAVOR OF CLEAN-ENERGY SUBSIDIES?

This is a nuanced question for me, because I believe that real-world governments tend to act in very inefficient and conflicted ways.

• I am in favor of cost-effective clean-energy subsidies, especially those relating to clean-energy research, development, and first deployments.
• I am against many stupid real-world subsidies, including subsidies for some clean-energy solutions. (For example, I am against subsidies for industrial CO₂ sequestration.)

237. ARE YOU IN FAVOR OF POLLUTION TAXES?

I am strongly in favor of reasonable pollution taxes, starting around $30/tCO₂ immediately and ramping up every year thereafter. I am especially in favor if the resulting tax revenue is used to reduce other taxes, rather than further increasing inefficient and dysfunctional government spending elsewhere.

238. IS THE WORLD (OR THE OECD) WAGING WAR ON CLIMATE CHANGE NOW?

The world is not waging war on climate change. In fact, spending on clean energy and emissions curtailment remains at least one, if not two, orders of magnitude lower than spending on defense.

239. WHAT ARE THE KEY ADVANTAGES AND DISADVANTAGES OF ELECTRICITY COMPARED TO OTHER SOURCES OF ENERGY?

• Advantages: Electricity is the most flexible form of energy. It has high efficiency when converting to other forms of energy (e.g., converting to kinetic movement). It can be transported instantly and easily (though with some losses due to electric resistance) over long distances. It can be cheap to generate, either from clean or dirty chemical fuels.
• Disadvantages: Electricity is expensive to store. The grid is expensive to build and maintain, so it will always have limited transmission capacity. Clean electricity is available only when nature wills.

240. WHAT ARE BASELOAD POWER, INTERMITTENT POWER, AND DISPATCHABLE POWER?

• Baseload power is generated by plants that operate around the clock (24/7). The best examples are nuclear and geothermal plants, with high fixed costs (of building) and low marginal costs (of running).
• Intermittent power is generated by plants that operate only when nature wills. The best examples are wind and solar power plants. They usually have zero fuel costs.
• Dispatchable power is generated by plants that can be turned on and off by an operator at will. The best examples are battery plants and hydro dams. They are usually turned on to cover periods of high demand and low intermittent supply. Their electricity is far more expensive than that generated by baseload and intermittent plants. It is the most valuable form of electricity.

241. WHAT IS THE DIFFERENCE BETWEEN A PLANT’S POWER (GW) AND ENERGY (GWH) RATING? WHAT IS A CAPACITY FACTOR?

Think of the plant’s power what it can generate at a moment, and a plant’s energy for how long it can generate this power. The “capacity factor” of a plant describes how frequently it is running. Some plants (like nuclear plants) run almost 365/24/7, so a plant with a 1 GW power rating produces about 8,500 GWh per year. Other plants (like solar farms) typically run only 5-6 hours per day, so a 1 GW solar plant may produce only 2,000 GWh per year.

242. WHY DOES THE WORLD NEED MORE DISPATCHABLE POWER (AKA ELECTRICITY ENERGY STORAGE)?

The world needs more dispatchable power to cover high demand and low supply.

• Supply: Dispatchable power has to fill in the gaps in clean but intermittent power generation.
• Demand: Much peak energy demand occurs after sunset (and some at night), when there is no solar energy; and during extreme weather spells.

243. FROM WHAT SOURCES IS ELECTRICITY GENERATED TODAY?

Electricity today is sourced from the following:

244. FROM WHAT SOURCES WILL ELECTRICITY BE GENERATED IN THE FUTURE (FORECAST)?

The EIA expects the following energy generation:

If the EIA is correct, then solar and wind farms will largely cover most new plant construction and worldwide demand.

245. IS THE USE OF COAL DECLINING?

Although coal is declining in relative terms (as a fraction of all energy), it is not expected to decline in absolute terms. Its total use is expected to be higher in 2050 than it was in 2020. (Much of the absolute increase will occur in China.)

246. WHAT IS THE “LEVELIZED COST OF ELECTRICITY” (LCOE)?

The LCOE is a measure of the cost of energy generation over the lifespan of the plant, including installation (and connection to the grid), operation (fuel, labor), capital costs, etc. It is usually quoted per MWh. The LCOE differs across plants and locations. For example, the LCOE of solar plants in California is lower than it is in the United Kingdom.

247. DOES THE LCOE MEASURE THE MARGINAL COST OF GENERATING ONE MORE MWH OF ELECTRICITY?

A marginal cost is one that is incurred for creating just one extra Wh of electricity. Because most plants have already been built, this cost is quite low. The LCOE is not the marginal cost of electricity generation, because the LCOE includes the price of construction whereas the marginal cost does not.

The LCOE matters when deciding whether to build a plant or not. The marginal cost of electricity generation matters when deciding whether an existing plant should come online or not.

248. WHAT IS THE LCOE OF ELECTRICITY GENERATION IN THE USA TODAY?

Although the cost of electricity generation varies by location (even within the United States!), the following is a rough guide to the LCOE per MWh of electricity generation in about 2021:

(NatGas peaker plants have costs of $150-$200/MWh.) Prices have generally gone up since then, even in inflation-adjusted terms.

249. WHAT IS THE FORECAST LCOE OF ELECTRICITY GENERATION IN THE USA IN 30 YEARS?

Although the cost of electricity generation varies by location (even within the USA!), the following is a rough guide to the LCOE per MWh of electricity generation in about 30 years:

250. WHAT IS THE TYPICAL RETAIL PRICE OF ELECTRICITY IN DIFFERENT COUNTRIES?

251. WHY DO SOME NATGAS PLANTS HAVE AN LCOE OF $40/MWH, WHILE OTHERS HAVE AN LCOE OF $150-$200/MWH?

There are two different types of natural gas plants:

• Combined-cycle (CC) gas plants run all day long (24/7) to produce base power. These have the $40-$45/MWh LCOE quoted above.
• Peaker gas plants typically run only in order to generate dispatchable energy. Their LCOE is typically 3-5 times higher than that of combined-cycle plants. These have the $200/MWh LCOE quoted above.

252. WHAT IS THE MARGINAL GENERATION COST OF ELECTRICITY AT NOON?

It depends on the location. In many places (e.g., in California), there is already so much photovoltaic solar power installed that electricity is usually sold at a spot price of zero or near-zero prices to the grid operator. In fact, plant operators sometimes pay the grid to shed excess electricity onto the wires. This is also why windmills are often turned off around noon.

253. WHY IS DISPATCHABLE POWER SO CRITICAL TO A CLEAN-TECH FUTURE?

Clean electricity generation is already as cheap or cheaper than electricity from any other source per MWh (although the details vary by location). However, the cost to store one MWh (produced at $30-$50/MWh today, $20/MWh in 20-30 years) and dispatch it later is about $150-$250/MWh. This is why combined-cycle natural gas turbines can still provide 24/7 electricity much more cheaply (at about $45/MWh) than solar photovoltaic cells1 and wind farms combined with battery storage.

254. CAN MORE ENERGY BE STORED IN DAMS AND UNDERGROUND CAVES FOR DISPATCH POWER?

Some countries could indeed build more storage capacity in water dams and in underground caves. However, the fixed cost of building such storage remains very high. It is therefore also limited to only the most suitable locations. Moreover, it is also possible that the large construction cost could be wasted even before such a storage plant would open if there were to be a battery storage breakthrough. Batteries can intrinsically store more energy and be located anywhere.

255. DOES HUMANITY NEED MORE ELECTRICITY STORAGE FOR GENERATING HEAT?

The world will indeed need more heat, but it will not need more electricity storage for later making more heat. It usually makes more sense to convert electricity immediately into heat and store it (e.g., in molten salt) than to store the electricity and convert it into heat later. However, it will also take time to convert some existing plants to stored-heat operations. Typically, designs change when old plants are replaced by newer ones.

256. WHAT IS THE COST OF ELECTRICITY STORAGE?

The cost of electricity storage per MWh today is about

It is here that most clean-energy research should be focused and where most future breakthroughs are needed (and expected).

257. SHOULD WE GENERATE SOLAR ENERGY IN THE SAHARA?

It is too expensive to transmit power over long distances, even ignoring transmission losses. For example, it is about 3,000 km from the Sahara to Germany. The cost to build as small a transmission line as one carrying 1 GW transmission over this long a distance can reach $2-3 billion. It is simply cheaper to accept less solar energy in Germany itself.

258. HOW MUCH ELECTRICITY STORAGE WILL A CLEAN GRID NEED?

The amount of storage needed depends on the percent of the grid that is to be clean:

Currently, all electricity grids have only a few minutes of storage. This is not a problem, because clean energy has not reached anywhere near 50% of grid provision. Reaching the first 50% milestone will pose no significant economic challenges. Going towards an 80%-clean grid will be modestly more difficult. However, the distant future should not be our main concern today. The main concern should be getting to 50-80% asap.

California has enacted laws targeting a 100% clean electricity grid by 2045. Achieving the last 5% will be more expensive than achieving the first 95%.

See also Q 142.

259. DOES THE ELECTRICITY GRID NEED TO BE EXPANDED?

Energy grids even in developed countries need to be able to transmit between two and three times as much electricity as they do today if their energy systems are to turn clean. (They will have to cover more transportation and heating needs.) Because expanding the electric grid will take a lot of time (and is hampered by large numbers of regulations), countries better start sooner rather than later with expanding their grids.

260. CAN SOCIETY LEAVE ELECTRICITY GENERATION AND TRANSMISSION TO THE FREE MARKET?

We cannot leave electricity generation and transmission to the free market, because transmission is a natural monopoly. It makes no economic sense to construct two different parallel grids. However, the owner of the single grid would always want to take advantage of her monopoly. This is why government regulation is necessary. (Unfortunately, government regulation is also often inefficient and in this case also hampered by overlapping jurisdiction and politics.)

261. CAN SOCIETY LEAVE ELECTRICITY GENERATION AND TRANSMISSION TO REGULATORS?

We cannot leave electricity generation and transmission to regulators, because the profitability and execution are far too difficult to be fully planned. The free market needs to help determine where to build plants and when to provide electricity. (Unfortunately, an unchecked market would not only eventually result in a monopoly, it would also come up with such “economically efficient” solutions as putting a nuclear power plant right into the middle of Manhattan.)

262. WILL ELECTRICITY USERS ACCEPT AN UNRELIABLE GRID?

Modern users in the industrialized world will probably not accept an unreliable grid. All modern economies depend on fairly reliable grids. (None have been 100% reliable!) In countries without reliable electricity where power outages are common, many parties (hospitals, wealthier individuals) have purchased private generators that work on diesel fuel (and are highly polluting). As more people install home solar panels and batteries, the reliability of the national grid may become less critical.

263. WHY DON’T WE BUILD PLANTS (STUFF) THAT LAST FOREVER?

At some point, building more lifespan into plants (stuff) becomes very expensive. It also must be considered that newer plants (stuff) will be more efficient, so it makes little sense to spend money upfront on longer expected lifespan. This is especially pertinent now for solar photovoltaic and battery farms, because their costs are expected to decline 2-3% every year. Most electricity plants have planned design lives of 30-50 years.

Despite some environmentalists’ conspiracy theories, “designed obsolescence” for business reasons is rarely advantageous for competitive companies. A company that artificially reduces the design lives of its products in order to make more sales in the future again will simply be driven out of business by companies that offer their customers products with better design lives.

264. ARE FOSSIL FUELS GOOD FOR ENERGY STORAGE?

Fossil fuels are nearly ideal for long-term storage. Their chemical-bond-based storage is very energy dense and easy and safe to store.

The chief drawback of batteries is that ion-based storage has two orders of magnitude (100x) lower energy storage density than fossil fuels. Moreover, a Lithium-based battery farm is based on individual cells, and thus twice the capacity costs about twice as much. (Flow batteries hold the potential of changing this situation, potentially making it possible to double energy capacity for a 30% increase in cost. These are not yet commercially viable, however.)

265. WHAT IS THE CHIEF DRAWBACK OF GRAVITY ENERGY STORAGE (SUCH AS HYDROELECTRIC DAMS)?

The chief drawback of gravity-based storage is that their energy density is one order of magnitude (10x) lower than even that of batteries. However, it usually does not cost twice as much to build a reservoir that is twice as large. For large amounts of energy storage, such as those required for full-overnight provision of energy, gravity storage often remains cheaper.

266. ARE ELECTRIC CARS OR HYDROGEN CARS BETTER?

Electric cars are intrinsically more efficient than hydrogen cars. By the time green hydrogen is catalyzed and put into the vehicle, about half of the original energy input is already lost. Another half is lost in making the vehicle move. In contrast, an electric vehicle can put about 70% of the original input energy on the ground. Thus, any transport vehicle with access to the electric grid will almost surely always be more efficient with batteries than hydrogen. Hydrogen will realistically only be a viable transportation fuel when there is no grid access (e.g., as in airplanes and ships).

267. IS HYDROGEN A GOOD SOURCE OF INDUSTRIAL HEAT?

It will likely always be better to convert electricity directly into an insulated heat reservoir rather than to first convert electricity into hydrogen and only later convert this hydrogen into heat.

268. ARE FOSSIL FUELS A GOOD SOURCE OF INDUSTRIAL HEAT?

Fossil fuels are a superb source of industrial heat. Fossil fuels are a one-trick pony capable of providing high-quality heat at low cost and this is their trick. This feature of high quality heat at low cost will make them difficult to replace with electricity.

A natural cost-effective alternative would be heat generated by nuclear reactors. However, it will likely remain (too) expensive to clear the regulatory hurdles and safety and proliferation problems in order to use them in most places where industrial heat is needed.

269. WHAT ARE GMO?

Genetically Modified Organisms. Although all food crops have been genetically modified by humans, this usually refers to changes made to the genome in the labs, rather than changes achieved through random methods (such as radiation) or selective breeding. GMO foods have been widely planted, sold, and consumed in the United States for over twenty years now.

270. SHOULD GENETIC ENGINEERING PLAY A ROLE?

Modern genetic engineering holds the potential not only to reduce the use of fertilizers (responsible for nitrous greenhouse gases) but also to curtail the use of herbicides and pesticides. Selective breeding and genetic engineering could further reduce the methane production of cattle and rice. GMO seeds could increase the nutritional value of the crops and make them more drought-resistant.

The dangers of genetic engineering in these contexts are remarkably low. (They do require some safety regulations and better guidelines restricting monopoly control by seed companies.)

It would be a terribly wasted opportunity for humanity if GMO technologies were not advanced.

271. WHAT ARE “SUPER-EMITTERS”?

This term usually refers to NatGas (methane) super-emitters — often from abandoned fossil fuel extraction sites, which are often sold late in their life cycles to smaller limited-liability companies that would later dissolve themselves in order to avoid all legal liability.

Cleaning up such methane super-emitters would be among the cheapest ways to slow down the increasing speed of global warming. However, most super-emitters are located outside the United States wherever fossil fuels were extracted, such as in Canada, Russia, and the Middle East. (Addressing super-emitters in the context of climate negotiations would be highly advisable [and affordable].)

272. HOW CAN HEATING AND COOLING COSTS BE REDUCED?

About 1/3 of our energy is related to heating and cooling our habitation. There are a number of ways to reduce heating and cooling costs without great expense.

• Insulation: Better insulation is a no-brainer. Up to 30% of energy today is used to generate heat or cold.
• Heat Pumps: Heat pumps shuttle heat and cold from and to the ground, rather than create heat and cold anew on demand. In many locations, heat pumps can cut heating and cooling bills by 2/3 relative to furnaces and air-conditioning.
• Thermal Storage: Both cold and heat can be stored in reservoirs when electricity is cheap and released when it is needed.

However, all three solutions require upfront capital investments. Governments may be able to offset upfront costs with better incentives and building codes. Governments can also extend targeted low-interest financing and promote adoption in other ways.

273. COULD HUMANKIND MOVE EARTH?

The question of whether we could move Earth was made famous by a question from Rep. Gohmert to a U.S. Forest Service official — to which the official — to her credit — did not burst out in laughter but replied that she would have to follow up with him.

The answer is no. It is not possible to move the planet. Recall that RCP 6 (our most likely warming scenario) is about an extra 6 W/m² due to anthropogenic GHGs. To reduce solar radiation arriving at Earth by 1 W/m² (from about 1,100 W/m²) by moving Earth’s orbit would require an orbital push equivalent to the total solar energy arriving at Earth for hundreds of thousands of years. In turn, this is equivalent to a few hundred million years’ worth of humanity’s power consumption.

274. WHAT IS CARBON SEQUESTRATION?

It is removing CO₂ from the air. Industrial sequestration is far too expensive to make sense.

275. WHAT IS THE COST OF CARBON SEQUESTRATION?

• The cheapest solution is reforesting with harvesting of lumber. In fact, converting aerial carbon dioxide into wood has already been estimated to be profitable in many parts of the world. That is, cost estimates are $0/tCO₂ — although the cost would, of course, increase the more trees were to be planted and the more CO₂ (say 1-5 GtCO₂) were to be removed.1 Importantly, to be economically so advantageous requires felling the tree and selling it on the market as timber, rather than allowing trees to die, decay, and eventually burn in forest fires. Given the versatility of wood, it seems unlikely that the world would not be able to absorb a lot more wood as a commercial good than it does today.

• The next cheapest sequestration solution includes schemes that accelerate stone weathering or ocean absorption of CO₂. However, such solutions have never been implemented at large scales. Cost estimates are on the order of $50-$100/tCO₂. Given that few decision-makers around the world have been spending even the lower amounts that sequestration by trees cost, it seems unlikely that the same governments would be prepared to spend this much more on a large scale on stone weathering or ocean absorption.

• Scientists are exploring schemes to speed up the absorption of CO₂ in the ocean and neutralizing it there faster (e.g., through ocean liming). These schemes require much more research. Their costs are difficult to assess.

• Industrial carbon sequestration is economically nonsensical. Cost estimates are on the order of $200/tCO₂ today and forecast to decline only to about $100/tCO₂ eventually in the far future. The only reason why such projects have been economically viable at all is because governments have enacted many stupid subsidy programs.

Note also that one alternative to sequestration is not to emit CO₂ in the first place. This is also much cheaper for the first million tons of CO₂.

However, as discussed, countries and decision-makers have little incentive to want to incur these costs on behalf of the world in total. The fact that the world cannot even take on solutions that cost under $5/tCO₂ speaks volumes about its willingness and ability to fight emissions.

276. IS IT POSSIBLE TO SHIELD EARTH FROM SOLAR RADIATION?

There are many ways to shield Earth from solar radiation.

• Schemes that involve space-based umbrellas to shield Earth from solar radiation are far too expensive. They are nonsensical science fiction.
• The most well understood solution is “Stratospheric Aerosol Injection,” discussed in the next question.
• Engineers are exploring whether they can create more artificial cloud cover, which could again increase the reflectivity of Earth. Unlike injecting sulfur dioxide into the stratosphere, it is not known whether this strategy is feasible or cost-effective. The advantage would be that clouds do not cause acid rain.

277. WHAT IS “STRATOSPHERIC AEROSOL INJECTION”?

“Stratospheric Aerosol Injection” is a form of “solar radiation management.” Engineers would inject sulfur-dioxide particles into the stratosphere, most likely from airplanes. The consequences are well understood, because volcanoes have been doing this forever. Sulfur-dioxide particles increase the reflectivity of the atmosphere and cooling happens almost immediately. The particles stay in the atmosphere for a few years and then rain back down to Earth. Thus, this intervention can be reasonably quickly stopped again on demand.

Atmospheric sulfur-dioxide seeding is two orders of magnitude cheaper and faster than cooling Earth by reducing CO₂ emissions. However, sulfur-dioxide shielding does not solve the underlying problem of too much CO₂ in the atmosphere. For example, it does not counteract the acidification of the oceans. Sulfur dioxide also ultimately causes more acid rain, which is (modestly) harmful to trees and oceans.

278. SHOULD ENGINEERS SHIELD EARTH TO LOWER ITS TEMPERATURE?

Scientists do not understand all the effects of intervention well enough to fully anticipate their potential side effects. There is a serious danger that such intervention could have unforeseen and unintended consequences (beyond acid rain). These risks of geoengineering still outweigh the benefits of intervention because climate change has created only modest damage so far.

Scientists widely agree that it is important to research such interventions. Decision-makers should be capable of deploying them if feedback loops or tipping points were to rapidly accelerate warming. Hopefully, they will remain last resorts that governments will never have to use.

279. WHY ARE MANY ACTIVISTS AGAINST GEOENGINEERING?

Activists are often instinctively against engineering of any kind. They are especially opposed to geoengineering. This overlooks the fact that humans only developed because of the largeest geoengineering of them all, called agriculture. Geoengineering has formed the basis of all forms of modern civilization.

280. WHAT IS THE MORAL HAZARD ARGUMENT AGAINST ATMOSPHERIC SULFUR INJECTION?

Many activists fear that this will provide an excuse for the world not to reduce CO₂ emissions. This fear seems unfounded. The world doesn’t need an excuse not to reduce CO₂ emissions. It doesn’t reduce its emissions, because it is not in the self-interest of its acting countries and people. This is the case whether or not there is the last resort of sulfur injection.

281. WHAT ARE THE MOST EFFECTIVE WAYS OF FIGHTING CLIMATE CHANGE?

My views are as follows (and there is some room for disagreements on this answer). Having thought about the alternatives and emphasizing the need for solutions also to work in non-OECD countries, I submit the following opinions:

1. Accelerating clean-technology progress remains the most effective way to expect to reduce fossil fuel emissions worldwide. This can be done with research and development subsidies, improved education, technology transfers, etc. — though these measures will not be easy to achieve, either. The costs are modest relative to the potential benefits and can be in the self-interest of countries. (I am less sanguine with respect to direct clean-energy expansion subsidies.)
2. Country-based fossil-fuel taxation is in the self-interest of most countries. Such taxation cannot only lower emissions, but can also help advance clean technology.

There are also many other useful actions — such as those improving forestry and agriculture; reducing fossil-fuel, ethanol and other crazy subsidies; hunting down methane leaks; etc. — but none are as important as the above two.

282. WHAT IS THE CHEAPEST SOLUTION TO SOLVING THE CLEAN ELECTRICITY ENERGY-STORAGE PROBLEM?

The lowest-cost solution to reducing the need for electricity storage is to change the price of electricity to better reflect its generation cost. Electricity should be nearly free during daytime hours when the sun shines, and expensive after-hours when clean energy is scarce. Better pricing would incentivize the public to shift towards more clean electricity and away from dirty electricity. It would also reward poorer households who can watch more carefully when they consume electricity. Governments can aid this change by implementing appropriate information protocols and smarter grids, as well as by educating people about the advantages of changing their behavior.

As far as I know, there are no concerted efforts to make this change anywhere in the world today.

283. HOW CAN A CONCERNED GOVERNMENT INCENTIVICE MORE CLEAN ENERGY?

There are three obvious ways for the government to reduce the cost of clean energy.

1. The government could expand and improve the electric grid and subsidize the connection of clean energy to the grid. (Right now, grid operators charge clean energy forms more for connection because clean energy is so intermittent and strains the grid.)
2. In the United States, the government could make clean energy generation cheaper by leasing more Federal land at lower prices to clean energy providers. The same holds true in many other countries.
3. In most countries, governments could move more aggressively to reduce the red tape and long approval delays for clean-energy projects. This initiative could involve “concierge services” that help companies navigate the permit processes, and maximum periods within which agencies have to respond to applications.

These suggested actions are in addition to subsidizing clean-energy research and development.

284. CAN A CONCERNED GOVERNMENT REDUCE METHANE EMISSIONS?

Any government concerned about global warming can and should immediately move to reduce methane leakage — one of the most powerful greenhouse gases. (As noted in Q 86, although natural gas is relatively clean at the use point, incessant leakage at the extraction and along the pipeline renders natural gas about as dirty as coal.) Recent U.S. legislation has begun to address the local U.S. problem. Unfortunately, many of the leaks are not in the United States, but in Canada, the Middle East, and Russia.

285. SHOULD CONCERNED GOVERNMENTS NEGOTIATE INTERNATIONAL TREATIES?

There are a number of international treaties that could and should be attempted. Treaties are promising when the costs involved to signing countries do not greatly outweigh their benefits. (Reducing methane leakage for super-emitters is one of them.)

As I have stated repeatedly, although I would be in favor of international treaties to implement more widespread CO₂-taxation, I believe that such negotiations are not likely to yield real results. I believe that the important countries — especially those in non-OECD countries — will not find it in their self-interests to sign on and enforce these treaties over the generations that would be required for an effective treaty solution.

Here is an analogy: I am in favor of peace on Earth and lower military expenses. I just don’t think it will happen.

286. HOW CAN YOU REDUCE YOUR CLIMATE ANXIETY?

(Stop believing everything on CNN and NPR!) Know the facts!

Civilization will not come to an end. Estimates about the effects of climate change are on the order of 0.1-0.5% of worldwide incomes. Scientists predict that climate change will cause even less harm in richer and more Northern countries. In those places, climate change will be more of a nuisance (i.e., warmer summers and winters) than an existential problem for the overwhelming majority of the population.

These damage estimates are not biased to make climate change appear less harmful. Instead, they are shared by almost all scientists, including those working with the IPCC, whose general intent seems more to push the world towards a sensible reduction in GHG emissions. (The most alarmed scientists tend to emphasize other harmful [and real] harm that is likely to occur in some specific poorer countries.)

287. WHAT CAN INDIVIDUALS DO?

There is not a whole lot that individuals can do. Global warming is a big problem, and even millions of people together cannot make much of a dent. It takes billions. The best marginal individual contribution to fighting climate change would be to work on promoting sensible ways to fight it. These approaches include the promotion, research, development, and deployment of clean-energy solutions; and secondarily, the promotion of local carbon taxes that are in the local self-interest.1

I would further suggest spending effort on educating the public about what can and what cannot work to shift climate activism to where it can make a difference.

288. WHAT ARE ENVIRONMENTAL ACTIVISTS ACTUALLY IN FAVOR OF?

The following is my personal impression of what activists are in favor of. It is not based on a scientific survey. There are a wide variety of activists and environmentalists with different levels of tolerance to human intervention.

The most radical environmentalists are against almost all human activities. They are even against wind farms and the mining of lithium necessary for a clean-energy future. Their proposed remedies of a quick departure from fossil fuels would probably not allow the planet to continue carrying as high a population as it already has.

A more moderate activist organization is Greenpeace. Its purpose is to highlight the negative aspects of fossil fuels (and it does this usually quite accurately), but members do not consider the benefits of fossil fuels relative to the available alternatives. My strongest disagreement with Greenpeace is their total rejection of nuclear energy and genetic engineering, and their often instinctive aversion to capitalism and markets. Greenpeace is generally supportive of some clean-energy compromises, such as the erection of windmills and the mining of materials necessary for batteries.

289. WHO ARE YOU?

Ivo Welch is a chaired professor of economics at UCLA. He has been teaching a course on climate change, economics, and technology for a few years now. (The information in this FAQ is based on this course and his textbook.)

290. ARE YOU DEMOCRAT OR REPUBLICAN? DO YOU WATCH CNN OR FOX?

Neither. I would consider myself dead-center. I share some views with both parties and many views with neither. I would survive in neither party. In fact, I am appalled by both.

291. ARE YOU AN ENVIRONMENTALIST?

Yes, I consider myself an environmentalist. I also consider myself a humanitarian. Therefore, I cannot be an unlimited environmentalist. I am strongly in favor only of cost-effective interventions, rather than any and all interventions.

I want efforts to fight emissions and climate change and other environmental and humanitarian problems not to be primarily performative but to be effective and efficient.

I am dismayed by how much mental bandwidth the public spends on approaches that will never work. Thus, even further discussing them is often counterproductive.

I am also dismayed by how many government programs primarily serve to line the pockets of interest groups rather than help what and whom they should be helping — but as an economist I am not surprised.

292. ARE YOU A NIHILIST — SUGGESTING NOTHING IS USEFUL AND WE SHOULD THEREFORE GIVE UP??

On the contrary! There are many very useful approaches, both small-scale and large-scale. For example, I would immediately institute strong time-of-day based electricity tariffs and subsidize expantion of the electricity distribution grid. I would enact local fossil-fuel taxes in the name of reducing local pollution. And I would subsidize aggressively energy storage research and development, as well as subsidize first-of-a-kind plants that share their experiences with the scientific and public community.

However, it is true that I am against carbon footprint watching and United Nations approaches. You may view this as nihilistic. I view this as saving us from wasted efforts.

I am also for focusing on more immediate actions. For example, I would rather not debate whether we can extract 30 GtCO₂ via tree planting but instead focus on extracting the first 1 GtCO₂ via tree-planting as cheaply as possible within the next five years. We should primarily worry about crossing the bridges that are here and now, not about bridges we may reach in fifty years.

293. WHO HAS HELPED YOU WITH THIS FAQ?

A lot of this FAQ is based on my book with my coauthor Bradford Cornell, edited by Mary Clare McEwing. This FAQ was edited by her, too. I really owe both of them a lot of thanks.

294. HOW CAN YOU HELP ME?

Please leave a good review on Amazon. Please recommend the main Global Climate Change and this FAQ to your friends. In about 1-2 years, consider updating to the latest version. (Amazon does not allow me to offer free updates.)

295. WHAT IS A MORE UNUSUAL ASPECT OF YOUR DESCRIPTION?

I placed relatively more emphasis on the following:

• This FAQ explains that our OECD perspectives are too ethnocentric. “We” are not simply no longer as important as we think. (The quoted facts about their size differences are however entirely uncontroversial. They are just often forgotten in the heat of the argument.)
• The FAQ draws a starker conceptual difference between what can and what cannot be changed. It sucks that the sun goes down earlier at night in winter, but there is nothing that we can realistically do to change this. Therefore, we need not lament and argue about this. Readers may disagree about what can and cannot be changed, but they should not disagree that if something cannot be changed, then debating it is not particularly useful. (The distinction should also be entirely uncontroversial. It is just often forgotten in the heat of the argument.)

296. WHAT WAS YOUR MOST CONTROVERSIAL OPINION IN THIS FAQ?

I believe that United Nations negotiations about global CO₂ limits are futile. I simply cannot see non-OECD countries — the large majority of emitters today and in the future — signing onto such treaties and adopting GHG curtailment policies, because signing on would be against their self-interests. Therefore, I believe that debates over the worldwide social costs of carbon are largely futile and distracting.

Many other researchers and policy-makers are more optimistic about negotiated agreements — to the point where trust in worldwide processes has often become the centerpiece of their efforts and policies to slow down climate change. I hope they will be proven right and I will be proven wrong. I just don’t think this will be the case.

297. WHAT IS THE WORLD’S POPULATION, BY REGION?

In millions of people:

E-Asia is China plus the Far East. S-Asia is the Indian sub-continent. `e’ means estimated.

298. WHAT IS THE WORLD’S ENERGY CONSUMPTION, BY REGION?

Of the world’s 187 PWh primary energy consumption:

With the U.S. 232 KWh per person per day normalized to 1:

299. WHAT ARE THE WORLD’S ENERGY SOURCES, BY FUEL?

Dirty Sources:

Clean Sources:

300. WHAT ARE THE WORLD’S ANNUAL EMISSIONS OF GREENHOUSE GASES?

In Gigatonnes of CO₂ equivalents (GtCO₂e):

Energy use is 73%, Agriculture 20%, and the rest 7%.

301. WHAT ARE THE WORLD’S ANNUAL CARBON-DIOXIDE EMISSIONS, BY REGION?

In Gigatonnes of CO₂ equivalents (GtCO₂e):

Per-person, in tonnes of CO₂ per year:

(Not shown, China is 7.5.)

302. HOW IS THE WORLD’S CLIMATE CHANGING?

Relative to 1980, with forecasts from the IPCC’s RCP 6 scenario:

An aggressive activist reduction scenario (RCP 4.5) would lower the IPCC’s estimated temperature change from 1.6°C and 3.0°C to 1.5°C and 2.5°C in 2050 and 2100, respectively; and lower the sea-level rise in 2100 from 0.4m to 0.3m.

303. WHAT IS THE GENERATION COST OF ELECTRICITY FOR NEW PLANTS?

These are LCOEs (levelized cost of electricity) per MWh, at the plant:

Marginal and fuel costs are higher for coal and NatGas, then nuclear. The other technologies only have operating costs, not fuel costs. CC (Combined cycle) and Peaker plants use NatGas. Obviously, solar photovoltaic will be the cheapest source of electricity for new plants, but can deliver only when the sun shines. Remarkably, solar generation in Western states has already been quoted as cheap as $20/MWh — ! The future is now.

304. WHAT IS THE STORAGE COST OF ELECTRICITY FOR NEW PLANTS?

The following are LCOEs per MWh, at the plant:

Unlike other technologies, peaker plants have higher marginal fuel costs, but unlimited capacity on the U.S. pipeline grid.

305. HOW MUCH STORAGE DOES A CLEAN E-GRID NEED?

Grid-Storage Needed for A Cleaner Grid:

306. FROM WHAT SOURCES IS ELECTRICITY GENERATED?

Electricity Generation, In PWh:

Dirty electricity generation is primarily from coal and NatGas. Clean generation is primarily nuclear, hydro, wind, and solar. Almost all the growth in clean electricity generation from 2020 to 2050 will come from solar photovoltaic.